MacOS – How to change fn key function

I ended up with this problem, too, after upgrading from Snow Leopard to Lion. I really needed my F8 key working as a standard function key for my job. I also really didn't want to delete my entire symbolichotkeys plist, though, so I did some digging.

If anyone else is having this issue still, you can edit your com.apple.symbolichotkeys.plist (located in Library/Preferences) with a basic text editor. Once you're in there just do a search for the number 75. Keys 75 and 76 (76 is the slow animation for when you hold down shift) are the ones for F8 activating mission control. You can just delete those two entries and your F8 key will become just another normal F-Key again. F9 will still work for mission control and you won't lose any other hotkey settings either.

As usual, always make a backup of these files when you're messing with them.

Good luck to anyone else with the issue, and thanks to those here who'd already provided some input and answers.

I was able to replicate the problem. Here's what worked on my machine to fix it:

• Go to System Preferences » Mission Control
• Under Keyboard and Mouse Shortcuts, go to Mission Control.
  • If it's set to fn, set it to some other value (or the - at the bottom of the list to disable a keyboard shortcut for Mission Control).
  • If it's not set for fn, but fn keeps triggering it (which happened to me), change it to anything else, then change it back to the value you want it to have.

On my machine, that made fn stop triggering Mission Control.