You can check this article. *https://support.mozilla.org/en-US/kb/restore-previous-session Make sure Firefox isn't set to run in permanent Private Browsing mode (Always use Private Browsing mode; Never Remember History). *https://support.mozilla.org/en-US/kb/private-browsing-use-firefox-without-history *https://support.mozilla.org/en-US/kb/common-myths-about-private-browsing *Settings -> Privacy & Security<br>Firefox will: "Use custom settings for history" *remove checkmark: [ ] "Always use Private Browsing mode" On Mac closing Firefox can be more complicated because you can close all open windows, but keep Firefox running with the menu bar visible or minimized in the Doc. Make sure to use "Quit Firefox" with all windows still open, especially if you want to use "Restore Previous Session". Otherwise check "History -> Restore Previous Session" and "History -> Recently Closed Tabs/Windows".