Volume line and keyframe changes only work on one row of audio track

I am trying to change the volume of an audio track by grabbing/dragging the horizontal volume line on the track in the timeline up or down. The problem is that the audio file imported with two rows in the timeline, and the horizontal gray line appears on the top row, but not on the bottom row. I can totally flatten the volume on the top row, but when I play the video the volume is the same (presumably because the volume didn't change on the bottom row).

The same is true of using keyframes. I add keyframes to raise or lower volume in specific locations on the timeline, but the keyframes only appear on the upper row, not on the lower row--so it sounds like nothing had changed.

I know how to change the overall volume of both rows using right-click Audio Gain, but I want to use keyframes here and there along the tmeline.

The question: How can I get the keyframe volumes to be reflected in both rows of the audio track?

Thanks in advance!