EDIT: Actually, I think it’s this: disable Auto-fit track height in Edit/Preferences > Tracks:
Enabling it caused the problems you described to appear.
3.7.7 on Win 10 here. I’m not sure I understand whether clips or tracks are being moved and what method is used to move multiple at the same time and whether they are moved up or down, or to the top/bottom. I tried all the things I could think of and nothing caused the scrollbar to move.
At this point I would suggest resetting your settings like in:
If you’re willing to share your audacity.cfg (here or via direct message), I could try to reproduce it on my machine and try to figure out the reason. See Resetting Audacity | Audacity Support