If you would like to edit one channel leaving the other channel untouched, please follow the procedure described below:
1. Open your file in AVS Audio Editor.
2. Disable the first upper channel (grey it out) then highlight the second one either by:
- selecting the whole track with the mouse;
- clicking on Edit > Select All; or
- using "Ctrl + A" shortcut key.
3. Apply Mute effect to the highlighted area. As a result, the lower channel will be muted, whereas the upper one not (see screenhot 1).
4. Open the same file in the program once again (it will be displayed as "File(1)" in Files area).
5. Follow the same procedure as described above, but apply Mute to the upper channel accordingly (see screenshot 2).
6. After that edit one of the tracks (you can copy and paste, trim parts, etc.).
7. Now, in order to combine the channels, highlight the first track and copy it to the clipboard (right-click it and choose Copy).
8. Open the second track, make sure the yellow cursor is placed at the beginning of the track, then right-click it and choose Paste Mix.
9. Before you paste the audio you can change Amplify Selected and Amplify Paste parameters. If you would like to apply the same sound volume to both channels, choose 100% for both the parameters and click OK (see screenshot 3)
As a result, the first channel will be edited and the second one not (see screenshot 4).
Hope this solution will be useful for you.
Nice editing!