How to make Firefox Default Browser
Here are the simple steps to make Firefox your default browser.
  • Click on tools menu
  • Click on Options
  • Click on the Advanced
  • Click on General tab if its not selected
  • You will see a section there called System Defaults. Make sure you have the checkbox for "Always check to see if Firefox is the default browser on startup" checked.
  • Click on Check Now. This will check if Firefox is your default browser if not would give you option to make it your default browser.