How I just set firefox to my default within the last minute after updating to Windows 10 on my laptop from Windows 7.
1. Click on firefox icon on my toolbar (took 2 seconds.)
2. Was asked if I wanted to make firefox my default browser (took 1 second to say yes.)
3. Went to the default settings automatically and switched Edge to Firefox (took 2 seconds.)
Total time spent making firefox my default browser: 5 seconds.
That was so strenuous and tough to do. I don't know how anybody without the technical expertise that I have could do that.