Hi Greg,
This post has a happy ending but I wanted to delineate the scenic route I took to get to the solution:
Go to C:\Program Files\Adobe\Photoshop Elements 2023, right click on the PhotoshopElementsEditor.exe file and click on Properties>Compatibility>Change high DPI Settings>Override high DPI scaling behavior>System Enhanced.
Of the links you provided, I happened to visit this link first:
https://community.adobe.com/t5/photoshop-elements-discussions/user-interface-on-screen-size/m-p/13375101
and wasn't sure what to do at Step 5, then I got distracted by the Compatibility Troubleshooter found under the Compatibility tab and I clicked it, but it brought up somethign about Windows 8 when it did the test that it didn't say beforehand, saying it fixed an incompatibility but didn't day what. Still, no change. Gosh I hoped I didn't add to the problem!
That's when I got back on track and visited your other link which I wished I would have read first as it talked exactly about my issue:
https://community.adobe.com/t5/photoshop-elements-discussions/photoshop-elements-2020-1-not-compatible-with-high-res-screen/m-p/11052998
and once I ticked the box at Step 5 and selected System Enhanced from the little pulldown menu, did the Update/Apply thing and restarted PSE2023, IT WAS FIXED!! HOORAY!! It now says Quick Guided Expert!
I bet that would have fixed my PSE 2015 on this 5K monitor but, oh well, like I wrote earlier, every few years I get the newer version anyway. It's not a trial, though, it's a no-subscription package with Premier Elements 2023 on sale for $99 until 01/03/23, then it goes back to $149.
I didn't know there were so many dang options under the hood as I never go exploring them. Also, it paid off that I happened to volunteer to post that Amazon link that spelled out the features, including the 5K monitor.
That's the happy ending. Thank you.
I didn't mention earlier but when I had clicked Edit to open the pulldown menu, the font of that menu had been HUGE, stretching all the way down the screen, but now they are the appropriate size. I will say that my icons in the left column, under the headings of View, Select, Enhance, Draw, and Modify are now larger than I think they ought to be, larger that they are in Video Editor, but they appear to be all there. I'm not going to call it a problem but if you happen to have a parting comment to adjust that, I will receive it.
In any case, when I click Edit/Peformance it still says Detected Graphics Processor is the UHD Graphics 750. In light of the happy ending above, is this really indicative of a problem with the configuraton of the cabling inside this All-In-One computer? Or maybe there is another tricky-dicky option in this PSE that would let me direct PSE to my other, better graphics card, my NVIDIA GeForce GTX 1650? Yet, this could be an issue unrelated to PSE, perhaps.
Thanks.