Photoshop 2021 - how to install plugins?

I upgraded to Photoshop 2021. Trying to install all my plugins, new versions. Nik, Topaz, etc... I go through the install script from each plugin. It says it's completed. Then I reopen PS, and the new plugin is not to found. The old version is there from the 2019 version of PS. How do I fix this? I've reinstalled various times with the same result. I see no instructions on this online. Please, if you have a solution let me know what it is.

How do I remove the old versions? They're not in the 2021 Plugins folder. How do I install the new versions? It's crazy that Adobe has changed how this works and made it so complicated and nonintuitive.

Thank you.