what happens when we click on “propagate all tracks”
There is no “propagate all tracks”.
Possible translation problem. Perhaps they meant “Ripple All Tracks”. First, you need to understand Ripple. It means some operations like Ripple Delete and Ripple Trim will move all the clips that follow the current clip. Normally, this only occurs on the track of the current clip. The option “Ripple All Tracks” applies that same clip movement adjustment across all tracks from the point of change.
thank you very much for your explanation