Can I change the brightness on a secondary display?
On Apple displays, if you press Control-F1 or Control-F2 the brightness on a secondary display will adjust. I have tested this on my MacBook Air 2011 13&quot; and 27&quot; Thunderbolt Display.
Important note: You have to plug in the USB cable from the Display to the Macbook Pro in order that the keyboard shortcuts work.
If you're using a MacBook with Touch Bar, this works for the &quot;brighter&quot;/&quot;less bright&quot; Touch Bar buttons but NOT for the Touch Bar brightness slider.