When I press the Function keys (F1-F19) nothing happens. How do I use the Function keys?
By default, macOS uses the F keys to control items such as volume and brightness. To use an F key for a game command hold down the fn key, then press the F key you wish to use.
To automatically enable the F keys, follow these steps (depending on the version of macOS you are running):
Open System Settings ( Menu → System Settings).
Click on Keyboard.
Select the Keyboard Shortcuts button (macOS Ventura).
Click on Function Keys (macOS Ventura).
Turn on Use F1, F2, etc. keys as standard function keys.
The F keys will now work without using the fn key.