Any time you choose to have Mozilla Firefox save your passwords to easily log into a page the next time you visit it they're stored on your computer. All of these passwords are also visible to anyone who goes into the security options of Firefox. To help secure your password information from anyone else using Firefox or from anyone that could steal your computer follow the below steps to setup a Master Password.

  1. Open Firefox and click Tools and then Options.

  2. In the Options click the Security icon option.

  3. Check the Use a master password.

  4. Enter your master password and click ok.

To view Saved Passwords click the Saved Passwords... button and then click Show Passwords. If the master password has been setup properly you'll be prompt for a password before being able to view all saved passwords.

This is one of the many reasons to never choose the option to save the password when logging into someone else's computer.