Not a very good tutorial at all. You have already setup the menu previously which opens options that would not otherwise be shown. Appearance > Menu I see no option at all to set a menu as default. If you have the pro version then you might want to say that in the title of this video. Following your video, the menu did not work at all, the menu's at the top were constantly organised in alpher numerical order and there seems to be no way to alter that.