How To Remember Website Passwords

Remember passwords for sites:

Firefox can securely save passwords you enter in web forms to
make it easier to log on to web sites. Clear this checkbox to prevent
Firefox from remembering your passwords.

Even with this optionpreference checked, however, you'll still be asked
whether to save passwords for a site when you first visit it. If you select
Never for This Site, that site will be added to an exceptions list.
To access that list or to remove sites from it, click the:
Exceptions… button.

Use a master password:

Firefox can protect sensitive information such as saved passwords
and certificates by encrypting them using a master password. If you create a
master password, each time you start Firefox, it will ask you to enter
the password the first time it needs to access a certificate or stored
password. You can set, change, or remove the master password by
by checking or unchecking this optionpreference or by clicking the
Change Master Password… button. If a master password is already
set, you will need to enter it in order to change or remove the master password.

Show Passwords…

You can manage saved passwords and delete individual passwords by clicking
the View Saved Passwords button.