CentOS - Sep 2020 - Forefox on C7 - uses wrong program to view download folder

I've got a C7 laptop using the default repo's (installed plus epel).

My firefox has decided to use the wrong program to view the downloads 
folder.

If I download and save a file, then click on the Downloads icon and 
click on view folder containing the file, it opens the MP3 editor 
EasyTag instead of Dolphin or Konquror.

How do I change it back.