Most email users have had that moment — you’re drafting a quick reply, scroll down, and realize your signature still says “Sent from my iPhone 6.” Whether you’ve changed jobs, updated credentials, or just want something cleaner, Outlook makes you hunt through settings differently depending on which version you’re using. This guide cuts through that confusion: step-by-step paths for desktop, web, and mobile, plus what to do when Outlook won’t let you edit.

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Official Guide Source: support.microsoft.com ·
Supported Versions: Desktop, Web, 365, Classic ·
Platforms Covered: Windows, Mac, iPhone, App

Quick snapshot

1Confirmed facts
2What’s unclear
3What’s next
4Key limitation
Setting Value
Primary Path Desktop (Classic) File > Options > Mail > Signatures
Primary Path Desktop (New) Settings > Accounts > Signatures
Web Path Settings > Accounts > Signatures
Mobile Path Settings > Mail > Signature
Official Documentation support.microsoft.com
Formatting Support Font, color, size, alignment, bullets, tables, borders, links, images (Microsoft Support)
Mobile Formatting Limited font and color options only (Microsoft Learn Community)

How do I change my signature in Outlook email?

Changing your Outlook signature starts with finding the right menu — and that depends on which version you’re running. The path differs between classic Outlook for Windows and the newer Outlook desktop app, so it helps to know which one you’re using.

Desktop application steps

For classic Outlook on Windows, the route is straightforward: navigate to File > Options > Mail > Signatures. Once there, you can create a new signature, edit an existing one, or delete ones you no longer need. According to Microsoft Support, users can format signatures with fonts, colors, and styles right in the built-in editor.

If you want more advanced formatting — bullets, tables, borders — Microsoft recommends creating your signature in Word first, then copying and pasting it into the Edit signature box. Microsoft Support notes pre-designed templates are available in Word to speed up the process.

Setting default signatures

Within the Signatures dialog, Outlook lets you set separate defaults for new messages versus replies and forwards. You can choose from your saved signatures or select “(none)” if you prefer to add them manually. When composing, you can also insert a different signature via the Message tab’s Signature button.

Bottom line: Classic Outlook for Windows gives you the deepest formatting control, but the navigation path trips up users expecting a modern ribbon-based menu.

How to change signature in Outlook 365

Outlook 365 runs two different desktop experiences depending on your tenant settings: the “new Outlook” and the classic version. Microsoft’s official documentation covers both, but the navigation differs significantly between them.

New Outlook toggle

In the new Outlook desktop, the signature settings live under Settings > Accounts > Signatures. This is a simpler path than the classic menu, but it requires knowing that “Settings” is the entry point rather than the traditional File menu. You can create multiple signatures, edit them, and choose which ones apply to new messages versus replies and forwards via checkboxes.

Microsoft Support notes that signatures in new Outlook support font, color, and styles directly in the editor. You can also insert signatures manually when composing a message via the Insert group’s Message tab options.

Web version settings

For Outlook on the web, signature settings are found under Settings > Accounts > Signatures. Like the new desktop version, the web interface lets you create multiple signatures, choose defaults for new messages and replies, and insert signatures manually when composing. The interface is consistent across browsers and devices, making it the most predictable option if you switch between machines.

Bottom line: The new Outlook and Outlook on the web share the same Settings > Accounts > Signatures path, but this catches classic Outlook users who’ve been navigating File > Options for years.

How to change signature in Outlook app

Mobile signature management in Outlook comes with a significant caveat: your mobile signature won’t sync with your desktop signature automatically. You’ll manage them separately unless you manually copy your desktop signature text over.

Mobile app iPhone

On iPhone or iPad, open Outlook and tap the menu icon (three horizontal lines) in the upper left corner, then tap the gear (settings) icon in the lower left. Scroll to find the Signature row and tap it to edit. According to Drexel University IT Support, you tap the chevron or text in the Signature row to access editing mode, and tap the back arrow to save your changes.

The iOS app’s signature editor has limited formatting options compared to desktop versions — you’re largely stuck with basic text, though Microsoft Learn Community confirms the app does support some font and color customization within those constraints.

Android and general mobile app

On Android, open Outlook and tap the Settings icon in the top right corner. Select Signature under the Mail subheading. The interface mirrors the iOS app, so the process is similar even if the menu placement differs. You can enter or paste your signature text, but advanced formatting like tables or borders won’t carry over if you’ve copied a desktop signature.

The catch

Mobile Outlook signatures have limited font selection and color options compared to desktop versions, according to Microsoft Learn Community. If brand consistency matters for your signature, you may need to simplify your design for mobile or accept that it will look different on phones.

How to change signature in Outlook Mac

Outlook for Mac has its own signature editor separate from the Windows desktop experience. The path differs slightly from what Windows users expect, and the formatting options are more limited than what’s available in Outlook for Windows.

Mac-specific navigation

On Mac, open Outlook and go to Outlook > Preferences > Signatures. From there, you can create, edit, and delete signatures. The Mac editor supports basic formatting — fonts, colors, and styles — but doesn’t have the same level of control as the Windows desktop version. You won’t find the advanced options like tables and borders that Microsoft recommends creating in Word for Windows users.

Like other Outlook platforms, you can set a default signature for new messages and replies separately. The Mac interface gives you checkboxes to control when each signature applies automatically.

Why this matters

If your organization uses Microsoft 365 and you’ve built a rich HTML signature on Windows, that same signature may not render correctly when you copy it to Mac or mobile. Testing your signature across all the platforms you use matters more than you’d expect.

Why am I not able to edit my signature in Outlook?

Getting locked out of your signature editor is a frustration reported across Outlook versions. The causes range from accidental navigation errors to policy restrictions your organization has imposed.

Common issues

The most common reason users can’t edit their signature in Outlook 365 is simple: they’re in the classic Outlook but expecting the new Outlook’s Settings menu. The two interfaces have different paths to the same feature. Users who expect “View all Outlook settings” to lead to signatures may find the option under “Accounts” instead, according to Microsoft Outlook Signature Tutorial on YouTube.

Another common issue: your organization may have deployed a signature policy via Microsoft 365’s Exchange Mail flow rules. When an admin uses “Apply disclaimers” to append organization-wide signatures, the Edit signature button in your personal Outlook settings may appear grayed out or behave unexpectedly.

Reset signature

If you’ve accidentally deleted your signature or the editor is unresponsive, the first step is to confirm you’re in the correct location for your Outlook version. For classic Outlook on Windows: File > Options > Mail > Signatures. For new Outlook: Settings > Accounts > Signatures. If the path is correct and you’re still having issues, try closing and reopening Outlook — the signature editor occasionally needs a fresh session to function properly.

For enterprise users whose signatures are managed by IT policy, you’ll need to contact your administrator. They can adjust or remove the Mail flow rule that’s affecting your signature settings, or they can update the organization-wide disclaimer to reflect your changes.

Bottom line: Can’t edit your signature? First, verify you’re using the correct path for your Outlook version. If it’s correct and still blocked, your organization likely has a policy in place — reach out to your IT admin rather than fighting the settings.

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Additional sources

youtube.com, youtube.com

Outlook on Mac requires slight variations, where the Desktop, Web, Mac & Mobile guide provides precise steps complementing our overview for web and mobile users.

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Frequently asked questions

How do I reset a signature in Outlook?

To reset a signature in Outlook, navigate to your version’s signature settings (File > Options > Mail > Signatures for classic Windows, Settings > Accounts > Signatures for new Outlook and web). Delete the existing signature text and replace it with your new content, or create a fresh signature from scratch. If the Delete button is unavailable, you may be working in a signature that’s applied via organization policy.

How to set up an email signature in Outlook?

Navigate to your Outlook version’s signature settings and click New to create a signature. Enter your desired text, format it as needed, and click Save. Then set it as your default for new messages, replies, or both using the checkboxes in the same dialog.

How do I add a signature to my Outlook email?

If you’ve set a default signature, Outlook adds it automatically to new messages and any replies or forwards you designate. To insert a signature manually when composing, click the Signature button on the Message tab and select the one you want. This works across desktop and web versions.

How do I automatically add a signature to a new email?

In your signature settings, use the checkboxes to select which signature applies to new messages and which applies to replies and forwards. Microsoft Support confirms that these options are available across new Outlook desktop and Outlook on the web. Classic Outlook for Windows offers the same functionality in its Signatures dialog.

How to add signature in Outlook permanently?

“Permanently” depends on whether you’re using per-user settings or organization policy. For personal signatures, setting a default via the signature settings means it applies to all new messages automatically. For organization-wide deployment, admins use Exchange Mail flow rules to append signatures as disclaimers — those can’t be edited by individual users.

How to change signature in Outlook classic?

In classic Outlook for Windows, go to File > Options > Mail > Signatures. Select the signature you want to change from the Select signature to edit dropdown, make your edits in the box below, and click Save. You can also create a new signature from this dialog and set it as the default for new messages and replies.

How to create signature in Outlook 365?

In Outlook 365 — whether using the new desktop app or Outlook on the web — go to Settings > Accounts > Signatures. Click New, enter your signature text, format it as desired, and click Save. Use the checkboxes to set it as the default for new messages and replies. Microsoft Support confirms that 365 supports multiple signatures you can switch between when composing.