Either: right-click on the cell you're double-clicking on, then:


2022-11-15_094254.png


Or: merely select the cell you're currently double-clicking on, then:

2022-11-15_094752.png

Either:

2022-11-15_095141.png

Or right-click anywhere in the pivot and choose Refresh.

No except that it might stop it expanding to the right if you want to add more columns to it, but more importantly, the comments will not move with rows added/removed when the source data changes and you refresh the pivot. That's why I suggested you copy/paste|Values the pivot to another location which then can't be refreshed, then you can add your comments there.
You could, instead of adding the comments to the pivot table, add them to the source data and include the comments in the pivot table.