See if the possible reasons provided in this article help to solve your problem: [[Username and password not remembered]].

-> click '''Firefox''' button and click '''Options''' * Privacy panel -> History section -> '''Firefox will: select "Use Custom Settings for History"''' -> REMOVE Checkmark from '''Permanent Private Browsing mode''' -> place Checkmarks on: ** 1) Remember my Browsing History 2) Remember Download History 3) Remember Search and Form History 4) Accept Cookies from sites -> click '''Exceptions...''' button and click '''Remove All''' button -> click Close 5) Accept Third-party Cookies -> '''Keep Until : select''' '''They Expire''' ** -> REMOVE CHECKMARK from CLEAR HISTORY WHEN FIREFOX CLOSES * Security panel -> place Checkmark on '''Remember Passwords for sites''' -> click '''Exceptions...''' button and click '''Remove All''' -> click Close -> Click OK on Options window -> Restart Firefox Check and tell if its working. -> IF you use '''Clear Recent History''' feature, DO NOT select '''Cookies, Forms and Search History, Active Logins, Site Preferences''' * https://support.mozilla.com/en-US/kb/Clear%20Recent%20History#w_what-things-are-included-in-my-history -> IF you use Privacy Cleanup softwares like CCleaner, DON'T SELECT FIREFOX IN ITS SETTINGS. These softwares can be responsible for Deleting your Firefox Settings.

Thanks all.... problem now solved :o)