Re: Moving a single audio track without effecting video/linked tracks

I wouldn't worry about it unsyncing. Final cut will warn you when your A/V are no longer sync by telling you how much the off sync is on the clip in red.

But if you just want 1 & 4 tracks being used, just set the Audio Track Activation tabs on the left of the timeline, (labeled A1 and A2) and clamp them onto track 1 and 4. Now when you insert or overwrite the clip onto the time line, the audio should split in those two tracks.