Hi pierlucperron, could I suggest this as the next step: '''Set up New Profile''' Inside Firefox, type or paste '''about:profiles''' in the address bar and press Enter/Return to load it. Click the "Create a New Profile" button, then click Next. Assign a name like Sept2020, ignore the option to relocate the profile folder, and click the Finish button. Firefox will assign this as your new default profile for external links and your next startup. After creating the profile, scroll down to it and click the '''Launch profile in new browser''' button. Firefox should open a new window that looks like a brand new, uncustomized installation. Is this what you're looking for? To avoid crossing over data with your other installation, '''do not log in to your Firefox Account on this profile.''' Later, if you do not want the earlier profile, you can delete it on the about:profiles page, but I suggest closing all Firefox windows and restarting before doing that.