Can't Get Audio To Work Properly

[Ethams]

I want to record two separate tracks, mic audio in mono and computer audio in stereo. Unfortunately, my "mix/aux" source seems to record both computer audio and mic audio for no apparent reason. that would be okay, if it recorded in stereo. however, since i have a two mic set up, when i change the mic/aux output to be stereo, i can only hear my mic audio in one ear. How can i fix this so that the "mic/aux" source only records mic audio