- Open a new private window with "File -> New Private Window" or short "Cttl+Shift+P"
- Visit some websites.
- Quit FIrefox completely.
- Re-launch Firefox.
- Check today's browsing history with "Ctrl+H".
vp1. New "Private Browsing" window should be opened.
vp5. There shouldn't have the histories of previous browsing websites.