I recently changed my Apple ID's email (and, consequently, the Apple ID itself), but I have the feeling that it didn't get updated everywhere. Namely, two apps -- Messages and FaceTime (which I only tried on the first day, and never used again) -- still have the old email/AppleID "hard-coded" in the login field. Is there any way to delete/change that? If I delete it from the field, it'll just come back in the next session. And if I want to log in, I only get prompted for the password (as the username is already filled with the old email/ID).
Also, just a few days after changing the email, I received a newsletter from Apple, sent to the old email. Go figure.
So far all other instances seem to have been updated properly.

(I was going to email Apple support for this, but I can't seem to find the right form on their website anymore; although I clearly remember that a couple of weeks ago, if the issue wasn't listed there, you were directed to a form which would in turn be emailed to them, and a real person responded to that.)