The setting works...in the way that if i quit Firefox, it'll not continue from the tabs and windows, but if i reboot my pc and open Firefox, I find myself the same place i stopped...even though i have that setting disabled. I found someone else with same issue on [https://www.reddit.com/r/firefox/comments/1aj3umy/how_to_prevent_firefox_from_starting_up_with_the/ reddit] and i did the same restarting the browser and refreshing and all....all to no effect.