Elizabeth,
I am having the exact same problem! Did you ever find a solution?
What happens to me is:
(1) I drag a video clip onto the timeline, onto the V1 track. The audio, predictably, ends up on the A1 track.
(2) But then, when I drag another clip, onto the V2 track, the audio, curiously, ALSO ends up on the A1 track, overlapping — and deleting — my existing audio!
Shouldn’t it go to the A2 track, thereby corresponding with the video track?
Richard