Hi anhnh1305, If you are using the desktop browser then: > In the top right corner of the browser you will see three horizontal bars, click them. > Fourth option, "New Private Window", click. > A private window should now open, this is the Firefox equivalent to incognito mode. If you are using the mobile browser app: > Open the app. > Again the top right corner is a small symbol of an eye-mask (masquerade style), click it. > Private tab opens. If don't use Mac or IOS, so my answers are only definite for Windows and Android. Best of luck!