In reply to both the message and the response... I have to disagree.. because I am doing that very thing and don't want it to!
I am having the exact opposite issue. My audio for ARMA II:OA (ARMA II works fine) will only work through my speakers, but then I can't use my USB headset and mic.
Here is what I have tried to remedy the problem.
1) uninstall ARMAII:OA (purchased via Steam), remove all instances of profiles I could find.
2) uninstall ARMAII:OA, removed all instances of profiles and cleaned the registry of all instances of OA.
3) uninstalled ARMAII:OA, removed all instances of profiles and cleaned the registry, ran ccleaner to wipe any files I may have missed. Disabled my onboard sound card in Windows so that ONLY my USB Headset was active.
And after each installation the profiles remained and the sound issue continued.
I don't know if Steam stores any of the profile information but I find it hard to believe I missed anything after 3 attempts.
Is there a file I can delete or edit to force a re-installation of the audio settings?
Chuckus, if I can figure out how I did it I'll be sure to let you know.