Firefox ignores my preference to NOT open previous tabs and windows on startup

Firefox OFTEN starts with a screen which reads, Sorry we are unable to restore previous sessions. OF COURSE it cannot restore previous sessions. I leave the box unchecked next to, "Open previous windows and tabs. I check the setting, delete all data on closing. I take great pains to delete data including cookies, website settings, etc, on closing, EVERY session. I NEVER want previous tabs, windows or sessions restored. HOW do I program FF to REMEMBER the setting, '''box unchecked''' next to "Open previous windows and tabs"