September 20, 2006 1:10 PM
First, make sure that you don't have something else plugged into the external microphone input. That will override the built in mic.
"Mixer" settings is a program on your computer that manages the volume and input levels for your computer's audio card. The problem is, every computer is a little different based on what audio chip and associated software is installed. Take a trip into the Windows Control Panel, and click on "Sounds and Audio" devices. Under the "Audio" tab, there should be a button labeled "volume" under "Sound playback" and "Sound recording" These should take you to the appropriate mixers. Hopefully that will get you on the right track.
There may be other software that contols your audio card, so you may need to do a little hunting around your computer for the appropriate programs.