Can I set Firefox to always use Private Browsing? In the Menu bar at the top of the screen, click Firefox and select Preferences. ... Select the Privacy & Security panel and go to the History section. Choose Use custom settings for history from the drop-down menu and check the Always use private browsing mode setting.

Regards, Jimmy

Thanks Jimmy but that wasn’t my question. I’m already using private browsing. Please reread my question.

Are you sure you closed every single Firefox window? The session persists as long as one window remains.

See if it still happens with all your extensions disabled.

The problem persists after shutting down Firefox. I have no extensions so nothing to disable.

Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile.

Refreshed existing profile. Then went into Settings and reset 'Always Use Private Browsing Mode.' 'Recently Closed Tabs' still appearing in History. There must be a way to disable this. Private Browsing isn’t private if it remembers your ‘Recently Closed Tabs?’

Recently closed tabs are only cleared after you close all private windows. You can disable it by going to about:config in the address bar and changing browser.sessionstore.max_tabs_undo to 0.

To terminate your Firefox session on Mac, make sure to use Quit, either:

• menu button > Quit
• (menu bar) Firefox > Quit

(As a Windows person, I don't know the exact wording, sorry.)

If you still have previous session browsing history or open/closed tabs after using Quit, maybe automatic private browsing isn't actually taking effect?