i have a macbook and a screen plugget to it. now i use just the new screen and dont use the macbook one. but every time i turn the mac on the macbook screen turns on, and i have to decrease the brightness manually every time. (cause it's a waste of energy to keep it on if i dont use it). so i'd like to know to set the screen brightness to 0 by default, so i dont have to turn the brightness down every time.