Hi, how do I remove “Get Outlook for IOS” from my email signature?

Hi, I have searched this all morning. Nothing is working. The signature shows as blank in the app. Even when I add a new signature, “Get Outlook for IOS” continues and my new signature does not show up. Is there a lock on this function? Because I need to put my work signature on my email, but cannot do it through the app signature.

thank you.