1. In the First step, you have to Log in to your Outlook account and go to the Mail app option.
2. Then, go to the settings and click Mail (Office 365) or Options (Exchange 2016).
3. On the left pane, extend the Mail section, then Layout and select Email signature.
4. To make signature looking in every new email message, check the automatically include my signature on new messages I compose box. Then, compose your email signature using available formatting tools.
5. Once your signatures have been created, hit the Save button so that all changes take effect.
6. Go back to your main Mail view and click the plus icon next to the new button or click the arrow and select Email message.
7. Your signature should be already applied to a newly opened message.