To Create a custom email signature, In Outlook go to File > Options > Mail tab, then click Signatures.
Click New and create a name for your signature. You can then edit the signature in the box below.
In the dropdown for New Messages and for Replies/Forwards, you can then specify the default signature whether it be (none) or one that you’ve created.
A signature can also be added to a new message by clicking the Signature dropdown then choosing the signature that was created.