Are you trying to use the Norton "Identity Vault" feature? Unfortunately, Symantec is still working on adding that back to its Norton toolbar for Firefox. It seems to be taking much longer than expected. They are now projecting August 2016 for a fully functional Identity Safe in Firefox.

https://community.norton.com/en/forums/identity-safe-limited-compatibility-firefox-current-status

For the time being, Firefox users are having to copy/paste passwords between Identity Safe (on the web, I guess?) and sites where they want to log in, or switch to a different password manager.

Also, there is a Tools menu on the classic menu bar, but that is not displayed by default. To show the bar temporarily, you can tap the Alt key. To show it persistently, you can use one of these methods to show the toolbar list and select it there:

• right-click a blank spot on the tab bar (or the "+" button)
• tap the Alt key to activate the classic menu bar > View > Toolbars
• in Customize mode > Show/Hide Toolbars (see: Customize Firefox controls, buttons and toolbars)

To turn on the Menu Bar, Bookmarks Toolbar, or other bars, click it on the list.

Also, on your Norton product settings: Toolbar options be certain that Enable Norton Safe Web is checked

I had tried to get this to work just yesterday Sept 20th 2016. I had issues getting this to work and the Norton Support agent went on Remote Control on my PC and finally said it will not work in Firefox. Nuff said for this deal!

It will not auto fill nor auto add passwords. But the Norton product does allow manual adding of new log ins/passwords. Then, one can copy to the clipboard, the password and paste it in the log in blank on the web site requesting it. OR as Norton puts it...USE Internet Explorer!