A: is two door speakers and two ceilings speakers.
B: turns off the door speakers and turns on all ceiling speakers.
Both: is all speakers (our speaker selector is a knob, not buttons)
If the rear speakers are not working then you need to look at the fade and balance on the head unit under the equalizer. If the fade & balance are set to the middle and on B or Both, then the connections could be bad???
You can play surround not only with a DVD but also with over the air and satellite. The TV has an audio out that goes back to the head unit.
Just search "playing surround sound" and you should be alb to find it.
PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).