Sync-Lock Tracks can be turned on or off at Tracks > Sync-Lock Tracks. Sync-Lock Tracks is off by default. Turning on Sync-Lock Tracks does not immediately realign tracks or labels. It forces tracks and labels to remain synchronized if they move after Sync-Lock Tracks is enabled.
What is sync lock?
Sync locks allow you to lock certain tracks together in order to keep them in sync with each other. Some NLE systems do this automatically, like the magnetic timeline in FCP X, but there are plenty of occasions where you don't want them locked together.