i have a similar set up with 4 separate mono ins. I’m away from the OT currently - hence the too short answer. sry 'bout that.
the playback set up page (double tap) will let you choose your input pairs (ie. A B) or just the single input (A) … i wouldnt be able to explain the cued outputs without sitting in front of the OT and am always scratching my head myself. that’s why I recommended reading up on - didn’t mean to RTFM (in case that came across)