1. Cannot insert between 2 clips. Normally, if I insert 1 clip between 2 clips, 2 clips will auto move. But this version will replace 1 of 2 clip instead of insert.
2. I’m not sure but when I extend first clip, second clip will auto move back but this is not. It will replace second clip. It mean the second clip will be shorter.
3. When I move 1 clip, all back side clip will be connected and moved together but this is only 1 move.
I think you’ve accidentally switched the mode from insert to overwrite with the button at the left of the timeline. Insert mode has the button arrow sideways as shown in this picture