Look at your audio devices in windows via the sound control panel. Make noise and see what microphones are picking up the noise. The check your audio devices in OBS. Originally I had 2 audio devices defined against eh same device. Yes you can do this. I am a drummer so I padded one down so the mic would not saturate while playing. The other defined as well but with less padding. I used it for voice. I just muted it in OBS before I started to play my kit.
Also you might try going back to simple mode vs advanced. at that point right click on an audio source and choose advanced audio properties. All audio sources should be in track 1. After that put each source in a different track i.e. everything gets track 1, desktop audio has 1 and 2, USB mic has 1 and 3, camera MIC has 1 and 4 etc...