I don't think it does that in PB as once you close it - it deletes any data or history or cache to clear your internet tracks.

You'll want to read up on PB as well.

https://support.mozilla.org/en-US/kb/private-browsing-use-firefox-without-history

I am not using PB or Private Browsing.

LAFfer said

It saves passwords for other sites. I am not in Private mode.

Hello LAFfer,

The login page on that website may be containing a piece of code that is used as a standard to tell the web browser not to prompt the user to save the password for security reasons. (added source code to the password input box that has an autocomplete=”off”)

From what I've seen on QuickBooks site, this just might be the
case ....

Maybe you'd like to post a question here :

https://quickbooks.intuit.com/community/Help-Articles/Application-is-not-allowed-to-automatically-log-into-QuickBooks/m-p/206370

The presence of autocomplete="off" hasn't been a reason for not Firefox offering to save the username and password since Firefox 30 (Bug 956906). A more likely cause is that the website uses JavaScript to submit the login form in the background via XHR (AJAX). Firefox doesn't detect the login form in this case (this only works via a normal form submit) and doesn't offer to store the password.

Thanks all. I guess I just need to remember my passwords.

cor-el said

The presence of autocomplete="off" hasn't been a reason for not Firefox offering to save the username and password since Firefox 30 (Bug 956906).

I should have remembered that Firefox ignores the "autocomplete=off" since version 38 :

https://developer.mozilla.org/en-US/docs/Web/Security/Securing_your_site/Turning_off_form_autocompletion

My bad .....

This autocomplete feature is accidentally hidden behind a pref.

• Bug 425145 - Hidden pref to save ID and password when autocomplete="off" (signon.overrideAutocomplete) [29]

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)