Disable the Internal Screen on a MacBook Pro or Air in OS X Yosemite & Mavericks Some MacBook Pro or Air users may want to disable their internal screen when the laptop is connected to an external display, this is generally achieved in two ways but ever since Mac OS X 10.7, 10.8, and 10.9, OS X 10.10 Yosemite, and OS X 10.11 El Capitan, the internal screen is more persistent and wants to stay on.