If a video clip has sound that you don't want moved when its video is dragged, sized, or a clip is inserted, first separate the audio from the video. Right-click on either track and UNlink. Here, when those actions are performed, the overlays do not move.
To keep independent, non-linked tracks from being affected lock them. Right-click to the left of the track and LOCK TRACK.
If you make a mistake, immediately press <ctrl-Z> to backtrack, step-by-step. EDIT menu | UNDO does the same.
For protection, Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar.