Whenever I'm working online in Windows 11, and want to insert a picture (e.g. profile picture on an account) Directory Opus doesn't open, but Windows defaults to/opens File Explorer. The reason I like Directory Opus is that it will allow me to preview the .jpg files; File Explore is having some real issues with file previews which is the biggest reason I downloaded Directory Opus. Is there a way to open Directory Opus instead of Windows File Explorer whenever I click to add a profile picture... as a matter of fact to substitute Directory Opus for all calls for File Explorer to open?
For opening files, Windows uses the standard dialogue which as Leo just linked, doesn't have anything to do with Directory Opus.
Personally I install shell handlers for files I need thumbnails for, as well as using DOpus thumbnails, just for this reason. Opening files with many similar names and not being able to see a preview is NOT an option for me.
But, in your case, jpg previews should work out of the box on Windows versions all the way back to XP.
You'll need to fix or patch over the original issue with your jpg previews not showing, because it's a sign that something is wrong with your configuration or registry. You could try SageThumbs to give you your previews back. It's very old now but should work.
Or, you might just have turned thumbnail previews off in your folder options...