I use FireFox portable 82.0.3 . When I select it as the default browser it sets the .pdf reader for the whole Windows OS as Firefox reader. I have the .pdf reader set in Windows as Adobe Reader. I also use Opera browser & some of the time I set it as the default browser. Opera doesn't change the .pdf reader when set to default browser. I know how to change it back to Adobe Reader in Windows but this is inconvenient every time I select FireFox browser as the default. I even set the Options/Applications to Portable Document Format (PDF) Use Adobe Reader in FireFox. If using FireFox & looking at a .pdf online FireFox uses Adobe Reader. When I click a .pdf in Windows the Windows uses the FireFox reader until I change Windows back to Adobe Reader. I would like to stop FireFox from setting the .pdf reader to FireFox reader everytime I choose FireFox as the default browser.