Master password for what site? Firefox forum only has password for the site to post and answer.

THE ONE ANSWER DID NOT ANSWER THE SERIOUS FIREFOX MASTER PASSWORD PROBLEM.

THIS IS A BAD PROBLEM THAT NEEDS TO BE CORRECTED OR PULL THE PROGRAM OFF THE MARKET. PEOPLE COULD LOSE THEIR LIFE'S SAVING BY POOR PASSWORD PROTECTION.

I have used the same 'primary' password for years, even changing profiles during that time. If you want to reset your primary password, refer to the following article.

https://support.mozilla.org/en-US/kb/reset-your-primary-password-if-youve-forgotten-it