Changed it but still not showing up. Might have to reboot. Time to cook dinner so will work on it later or tomorrow .
Nope, rebooting didn't help. Opening /home as admin doesn't do anything either.
GOT IT! Changed the file manager from Caja to Files, configured it to show hidden files, and there .config is. So I'm off to try that other suggestion now.
Don't have a mimeapps.list file in that dir so did a search and found it somewhere. Chging it now...will test.
FIXED Followed this instruction to rename this file: home/.config/mimeapps.list to mimeapps.list.disabled
I can now click on PDF files and they open in Atril instead of the ImageMagik splash screen opening.
The default for PDF is now Atril.
I'm changing my file manager to 'Files' too since Caja didn't change to show hidden files as requested.
I don't know how many other items this changed yet but I'll keep my eyes open.