TapNoiseThe top row on an Apple keyboard often controls brightness, media and volume. To send a standard function key such as F5, you may need to hold Fn or Globe while pressing it.
Try the temporary combination
Use Fn or Globe with the relevant top-row key and test it in the app that expects F1–F12. Check that app’s menu or keybinding list first: a function key has no single meaning across all Mac software.
On an external keyboard, there may also be a hardware Fn lock or Mac/Windows mode. Check the keyboard maker’s instructions if macOS settings do not explain what the key sends.
Choose the default behaviour
Look in System Settings › Keyboard › Keyboard Shortcuts › Function Keys for the standard-function-key option where available. Turning it on makes the top row favour F1–F12; Fn or Globe then provides the alternate media behaviour.
Use a reversible test. If you adjust volume more often than you invoke F-key commands, the original default may require fewer extra key presses.
Keep app controls distinct
A media play/pause key affects media controls; it does not necessarily pause a timer, terminal command or coding agent. TapNoise’s knock commands offer another way to trigger supported media actions on compatible MacBooks.
If a shortcut still does nothing, follow shortcut conflict checks. Avoid changing several global bindings before confirming what the app actually expects.
Source: Apple: use keyboard function keys.