Editing audio tracks in Garage Band

I would like to edit an audio track in Garage Band. I can cut and delete unwanted regions, but when I move the track to the beginning (00 time) to keep editing, it regains back everything I cut before. I tried to create a new audio track (New Track, not New Track with Duplicate Settings), but it does not help. The track is not locked. It is not a movie track, but .wav file. Could you please let me know why this track behaves like a locked/frozen, while it is not locked? I edited hundreds of audio tracks before and it never behaved like that. Thank you.