garageband multiple mics

WHY is it so complicated to record acoustically with 2 mics simultaneously on 2 separate channels in Garageband? I have great mics, interface & new mac mini. I've watched countless instructional videos outlining the process, but even after navigating the labyrinthine steps, it still seems to always want to default to only recording 1 mic, or both mics on the same channel (I need to be able to mix independently). This seems like a pretty basic function, I can't fathom the impetus of making it so difficult.