Steve, go into Device Manager and expand Sound Controllers to see what company's audio is used on your mobo (Realtek AC97 is a common one). With that info, go into Program Files and look for the appropriate company's folder; check all the .exe files you see until you find the control console and you can change your settings accordingly. (Arrange the folder icons by Type and they'll all be grouped together.)

If you never actually ran the app when you set up Windows, you may have to run the audio installer.