I have Adobe Acrobat Reader DC (on a MacBook OS 10.15.6) which I used to convert a file to a PDF. When I did that, there was a pop-up question which I answered YES but I forget now what it said. All my PDF files now have an Adobe icon in front of them and when I open the files they open with Adobe Acrobat Reader. How can I change them all back because I prefer they open in Preview?
First of all, Reader can't convert files to PDFs. Maybe you opened it in Reader, but you didn't create it there.
Secondly, the files were not converted. The only thing that changed is the default application associated with the PDF file type. The dialog probably asked you if you wanted to make Reader the default application for PDFs and you said Yes.
Thirdly, you should be using Reader, not Preview, anyway. Preview is a buggy app that corrupts PDF files just by opening them and should be avoided.
However, if you really want to do it follow these instructions: https://www.imore.com/how-set-mac-app-default-when-opening-file
Thanks so much for the education. I know I don't know a lot about this stuff but I get by. At least I used enough words to get you to understand my question. Perfect answer.
Wow! Good to know. Thanks!