The surround speakers in any surround sound system are for ambient noise or what would be considered "behind" you coordinating with the picture. If a car drives by from right to left behind what's being viewed on screen then you will hear that from the rear speakers only, starting from the right and fading out from the left. If you would like to hear the same thing out of every speaker then you can set your receiver to either extended surround, 5ch stereo, or 7ch stereo, but to fully experience what is intended out of your surround sound I recommend leaving it how it is.
