Quick guide on updating your email signature in Outlook and Outlook Web. 

Outlook App

Step 1: Click File -> Options -> Mail -> Signatures 

Step 2: Click the signature you want to edit or make a new one, and then edit your changes in the Edit signature box. 

Step 3: When you're done, select Save -> OK.

Outlook Web

Step 1: Click the settings cog wheel on the top bar. 

Step 2: Click View all Outlook settings, then click Compose and Reply.

Step 3: In the text box, create your signature as required, make sure the default options are set to Outlook web.