Thank you for this thread. It fixed my problem. Sad that Tech Support via some offshore customer couldn't help.
I had 2 problems, how to reset my remote to factory default and no sound on only HD channels. 5 phone calls to tech support trying to find someone who knew something was exactly zero help and a BIG waste of my time.
Then a simple Google and within minutes I had it fixed. AT&T charges a lot to watch TV in America, they should be ashamed of themselves for not employing Americans for their tech support