Question

How can I make Firefox automatically remember all passwords without prompting?

Answer 1

Hacking Firefox to Always Auto Save Password Without Showing Notification Bar:

1. Close Firefox
2. Edit nsLoginManagerPrompter.js with notepad which is normally located in C:\Program Files\Mozilla Firefox\components\

3. Replace the entire lines 642 to 711 with the code below:

   var pwmgr = this._pwmgr; pwmgr.addLogin(aLogin);

Now whenever you login to any website, Firefox will auto save the site, username and password to the login manager WITHOUT showing the notification bar.

Note: even when you enter the wrong username or password, it will still be saved.

Source

Answer 2

Looks like this site here has the answer you are lookin' for here

It states that you must have all instances of Firefox closed, navigate to the "C:\Program Files\Mozilla Firefox\components\" directory, open up nsLoginManager.js and comment out lines 112 and 121