Pick the right scope

A small interactive app sits on the right: a ticket list you can open, plus a panel where you pick where Set(visitCount, …) lives. Try all three options, open a few tickets between each switch, and watch how the visitCount behaves.

The same Power Fx call produces three completely different results depending on where you put it, and the visitCount and the explanation panel surface what changed. Which scope makes the counter count visits across the whole app, and why?