Creating a signature in Outlook online
Go to Sent Items, open any email you have sent and copy your signature.
Go to Settings:
This will take you to your Settings, go to tab Compose and reply. Click on New Signature:
Paste your signature in the Outlook signature box and add a signature name (ex : Standard):
Click Save a 1st time.
Scroll down the page to indicate when your signature should default then Save again:
After refreshing, we suggest you test creating a new email to confirm your signature looks the way you wanted, and validate the hyperlinks are functioning.