MDI Mainer wrote:
Apparently, if you have a clean install on an older computer, or a computer that came with Windows 10 as its original OS, you need to do a registry edit to reactivate Photo Viewer. That's probably too risky an operation for many, just to change photo programs.
But I agree this is another example of where the old program was more intuitive and better than its replacement.
I did not realize that the link helpfully posted by Max Bottomtime provides a hack to download and install which will make the registry changes automatically. In a fit of disgust with Windows Photos, I tried the hack and it worked flawlessly. So I'm back to using Windows Photo Viewer as the default program.