Hi   !
Go to the 3-bar menu ( ≡ ) -> Options -> Security -> and check the box that says   'Remember logins for sites'
See the article   'Password Manager - Remember, delete, change and import saved passowrds in Firefox'     http://mzl.la/1QTGGxf

Yes, that is that box, my problem is that i can't select it. And i don't know why.

hello, firefox won't save your passwords when you've set it up to run in permanent private browsing mode ("never remember history" in the options > privacy panel).

Settings for privacy, browsing history and do-not-track

okay thank you it's solved but firefox is very slow now

In what way is Firefox slow?

You can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

• https://addons.mozilla.org/firefox/addon/places-maintenance/

See also:

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• Do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Clear the cache and remove the cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Clear the cache":

• Firefox/Options/Preferences -> Advanced -> Network -> Cached Web Content: "Clear Now"

"Remove the cookies" from websites that cause problems.

• Firefox/Options/Preferences -> Privacy -> "Use custom settings for history" -> Cookies: "Show Cookies"