Double-clicking opens 2019 instead of 2021 after last update done in 2019

I had to use Studio 2019 when normally I use 2021. After opening Studio 2019 I was told there was an update. I ran that and now every time I doubleclick a package it opens by default in Studio 2019.

Why does it not ALWAYS and automatically open in the most recent version?   And how can I ensure that this happens after installation of an upgrade in a lower version.