In the montage, Ripple mode determines if all the clips to the right move or not. You can turn it on globally, montage per track, or turn it off. I have it on 99% of the time but now and then I need to turn it off.
I can’t remember if there are factory shortcuts to change the Ripple settings but I definitely programmed my own shortcuts.
You may also want to make sure Auto-Grouping is off. I don’t care for that feature and have never used it, it seems to just get in the way.
Anyway, here is where you find the Ripple setting:
