In this video a user shares how to use an external monitor as the main display on the Mac. For instance a recently purchased flat screen TV can be used as the primary display. So if you want to use your external monitor as your primary display then all you have to do is follow these simple stops. First, you have to open up settings and go to system preferences. After that, navigate to displays you will then see the option labeled arrangement. Once you are under arrangements, you will see two sets of displays. From this point all you have to do is to select the white bar and drag it to the other display . This will change your external monitor to be your primary display. After this is done you should notice that the Dock is now displayed on your external monitor and the taskbar should be on the top.