01
Edit or replace a signature.
Replacing is usually cleaner than editing a designed signature in place, because Outlook's editor can disturb the table it is built from.
- New Outlook and the web: Settings (gear icon), Accounts, Signatures. Classic Outlook: File, Options, Mail, Signatures. Mac: Outlook, Settings, Signatures.
- Select the signature you want to change.
- To edit, change the text in the box. To replace it with a new design, select everything in the box (Ctrl+A or Cmd+A), delete it, and paste the new signature.
- Click Save (or OK in classic Outlook).
02
Change which signature is the default.
In new Outlook and the web, the defaults are under Select default signatures on the same page: one for new messages, one for replies and forwards. In classic Outlook they are under Choose default signature, and are set per email account, so pick the account first.
03
A shorter signature for replies.
Long threads with a full signature on every reply are hard to read. Make a second, shorter signature (name and phone, say) and set it as the default for replies and forwards, keeping the full one for new messages.
04
Delete a signature.
Select it in the signature settings and choose Delete (the bin icon in new Outlook). If it was a default, set another one, or Outlook sends with none.
05
On your phone, and when a change does not show.
In the Outlook phone app, tap your profile picture, Settings, your account, Signature, and edit the text. It stays plain text.
If a change does not appear: check you edited the signature that is set as default for that account, restart classic Outlook (it caches signatures), and remember that emails already sent keep the signature they were sent with. If your signature comes from the generator, edit it in the builder, copy it again and paste it over the old one, because a signature already pasted keeps its old images and links.
Microsoft's own help page covers every version and is worth keeping open beside these steps, since Outlook moves its menus more often than most.