Click the Choose Signature pop-up menu, then choose a signature. In the Mail app on your Mac, choose Mail Preferences, then click Signatures. You may change the name of your signature by double-clicking on the name, and typing in the name you. Your new signature will automatically be named “Untitled“. On the menu bar, select Outlook Preferences Signatures. To create a signature in Outlook for Mac, do the following: Launch Outlook.