Is there a way to customize certain function row keys on Mac, without losing the functionality of others? I have a third-party display hooked up to my Mac mini and I want to use the standard F1 and F2 keys to control its brightness with a third-party app, but I can't find a way to do that without losing the correct functionality of all the other keys that I want to keep in place (like music controls, volume, etc). Is there a way to only customize certain function row keys while keeping all the other ones in tact, and if so, how to do this?

  • Your problem comes in that the 'Special Function' keys are not true F-Keys, so to reassign them you'd have to involve the Fn key for one 'half' of your shortcuts. You can assign an F-key to a menu item or a scripted Automator Service [which could be the trigger for many things] but you cannot reassign the Special Functions. What's the 3rd party app?
    – Tetsujin
    Commented Oct 17, 2021 at 18:44
  • It's called ExternalDisplayBrightness, its name basically implies what it does - allows you to control a third-party display's brightness using the Fn keys on your Mac's keyboard. I want to assign the raise/lower brightness function keys already on the keyboard to this utility so it works the same way, but I can't do that at the moment without disabling all of the other special keys' functionality. Currently those two buttons are useless since Apple doesn't allow you to do this natively with most external monitors. Commented Oct 17, 2021 at 21:34

1 Answer 1


To maintain the functionality of your other Special Function keys whilst also being able to map ExternalDisplayBrightness to, 'true' F-keys will require that you use them whilst holding the Fn Key.

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Assuming you set these to F1 & F2, then to action them you would press Fn F1 or Fn F2

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