Q: How do I set the incoming mail server in my Mail preferences? It will not let me enter anything but Mail keeps asking for my passwordrepearedly.

Mail preferences does not appear to register any of my keystrokes in the incoming mail server field, and will not let me save anything with that field apparently blank. I am trying to enter my durrent password, which is clearly OK, because I am logged in here and accessing iCloud in a browser, but Mail prompts me repeatedly for my password. How do I set the incoming mail server in my Mail preferences?