Correct me if I’m wrong… You change the tempo and events, that were in the correct location, move relative to the time signature changes?
If this is the case, what you need to do is change the track from a tempo base to a linear base. This will prevent the items from moving with tempo changes. In the track’s properties inspector (far left column), look for the orange note. Click that button and it will change to a gray clock. Then change the tempo and items should stay at the same timecode location.