https://support.mozilla.org/en-US/kb/how-make-web-links-open-firefox-default https://support.mozilla.org/en-US/kb/setting-firefox-default-browser-does-not-work https://support.mozilla.org/en-US/questions/1207775 https://support.mozilla.org/en-US/questions/1208759#answer-1086882 https://support.mozilla.org/en-US/kb/how-change-your-default-browser-windows-10 https://www.bing.com/search?q=change+default+browser+windows+10

So I unchecked the 'always check if Firefox is the default browser' box and that solved my problem. I'm wondering if the reason I had this problem is because I had 2 versions of Firefox on my computer. A version with the default settings and a version with all my extensions, bookmarks and preferences. Thanks Fred for the solution.

Glad to help. Safe Surfing.