How to get sound devices settings to hold?

I use the on board sound and I cannot get the speaker settings to stay at what I set them at in the "Sounds and Audio Devices Properties" screen. I set them at "desktop stereo speakers" and when I return to the settings screen, they return to "7.1 wide configuration speakers".How can I get the setting to stay at "desktop stereo speakers"? When it reverts, the sounds in FSX are terrible.Thanks a lot,Howard