Why can't I type in the subject line of my outgoing emails?

[Puzzled in Pensacola]

I cannot type in the subject line of outgoing emails, but I can type in the
message area. I also cannot type in the To and CC boxes, but I can choose
from the dropdown boxes when I click on To and CC. Any idea how to fix this?
Thank you!!

 

[Pat Willener]

What means "cannot" - what happens if you try? Also, give some more
details, like the version of Outlook, account type and message type.

 

[Pat Willener]

P.S. is that something that "suddenly" started, or has it always been
that way?