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Are you using a company computer that might have been configured by your IT department? You can check the <b>signon.rememberSignons</b> pref on the about:config page to see if the Status value shows 'locked'. If this pref is locked then something must be locking this pref to disable the Firefox Password Manager. You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue. *http://kb.mozillazine.org/about:config ----- If the pref is locked then check if there is a <u>mozilla.cfg</u> file in the Firefox.app folder to initialize (set/lock) preferences. */Applications/Firefox.app/Contents/Resources You can check this folder to see if there are files apart from channel-prefs.js file that sets app.update.channel. */Applications/Firefox.app/Contents/Resources/defaults/pref See "Changes Over Time" -> "Mac Directory Change" *https://developer.mozilla.org/en-US/Firefox/Enterprise_deployment_before_60 If there are .js files present in the "defaults/pref" folder apart from the channel-prefs.js file that sets app.update.channel then open this file in a plain texteditor like Notepad (Mac: TextEdit) and please post its content. Also please post the content of the mozilla.cfg file. There shouldn't be a mozilla.cfg file present unless you've created it yourself to initialize some prefs. If you have this mozilla.cfg file then best is to do a clean reinstall and delete the Firefox program folder to make sure that all files are removed before reinstalling a fresh copy of Firefox. *http://kb.mozillazine.org/Preferences_not_saved#Other_solutions