Getting more "surround" out of this surround sound

I just bought a Onkyo HT-S5400 and so far is seems pretty good. However, there isn't much "surround" to it. Under setup I have cranked the rear speakers but it still isn't immersive...like music doesn't fill the room.

Specifically for video, there doesn't seem to be a preset/setting that utilizes surround sound. In "theater" mode not a single one of the 4 rear speakers has anything coming out of it.

Am I missing something? Please help. I've read the manual front to back.
Thanks.

Hi Comma,

The surround speakers are just for "effect" when playing a movie. On some movies you may or may not hear any audio coming from the rear speakers as it all depends on the movie. If on the other hand you change the "listening mode" to "all ch st" that should put the audio to all the speakers that are connected.