How to activate speakers while watching TV?

[Marks mobile suite]

Guys, just bought a 05 Doubletree Mobile suites with very little manual info. The previous owner cant help. The suites has a Sound PKG with Sony FS. We get sound out of all the speakers while playing a music or movie cd. Just cant figure out how to turn on all the speakers while watching Dish satalite tv.

Thanks for any help. I'm sure its simple and I just cant see it. It seems were learning something new daily.

:D