Hi Dave, Firefox does not have a feature to lock out access to the browser, only access to your saved logins. (More info on that latter point: [[Use a Primary Password to protect stored logins and passwords]].) If you don't share your computer, you can use your Windows account to lock the computer when you are away from the keyboard (hold down the Windows key on the keyboard and tap the L key). But if you share a single Windows account with others, that won't really help. Maybe there is an add-on or external solution to lock the browser.