Note that these instructions are specific to using the signature in Outlook on the web for Microsoft 365. Other Outlook apps can use the signature, the process is similar.
After applying the correct signature settings, copy it:
In a browser, open your Outlook account (outlook.office.com/mail) and from the upper right navigate to:
Settings > Accounts > Signatures
Select the button:
Add signature
Give your new signature a name, then paste the previously copied signature into the signature editor. Use the options below the editor to apply it to new messages and replies or forwards, then select the button:
Save