Jeff,
No, your central folder suggestion doesn't work. The trouble is, I think, is that I'm working with PSE 2018 from the cloud. Consequently, I can't figure out (1) how to get plugins to work, nor (2) can I figure out how to uninstall PSE 2018 in order to download a version that is not in the cloud. Interesting problem to a Luddite like me, who simply wants to stick with what's familiar.
It's not a "cloud" program, but a program from the Microsoft store.
Here's how to uninstall Microsoft store apps:
https://support.microsoft.com/en-us/help/4028003/windows-10-uninstall-apps-and-programs
If you want a version of photoshop elements that is easier to install plugins, you want the pse 2018 version from adobe.
https://www.adobe.com/products/elements-family.html?promoid=V2XYKZ3B&mv=other
The problem with apps from the microsoft store is they are "sandboxed" so they are not like regular windows programs, where one has access to them.
https://www.howtogeek.com/243559/why-desktop-apps-arent-available-in-the-windows-store-yet/