firefox will not save my updated password

my work password changes approximately every 90 days, I have saved the changed password in the past and it will not accept this change. It asked me if I wanted to update, I agreed, it didn't save. I deleted the old password from the security section where the saved passwords are listed. It didn't save it. I then deleted the new one and logged into the site and it asked if I wanted it to remember the password, I agreed and it didn't . Why will it not save this password.