Also, there is no RGB scancode in the USB HID protocol defining 'change RGB'. Even though you may be a part of pcmasterrace, the OS does not know anything about RGB keyboards and lighting.

When you press the Fn + D keys, the QMK Firmware interprets this as change RGB Setting. It will not send the Fn key, because the Fn key only matters to QMK firmware, and not the OS. Now, when you hit Fn + Key(1,1), it will send the letter 'z' (scancode 0x1D) down the USB wire. This means that if you configured it, Fn + Key(1,1) could now send the letter 'z' (scancode 0x1D). For example, Fn keys are typically used to switch between virtual 'layers'.

There are some keys and that combinations which don't get sent down the USB wire at all. If you configure QMK Firmware to say that Key(1,1) is the letter 'a', whenever you hit Key(1,1), it will send the letter 'a' (scancode 0x04) down the USB wire. When you press a key on your keyboard the QMK Firmware inside the keyboard interprets the key presses and creates a set of keycodes of what exactly to send down the USB wire to the OS. QMK has a good diagram of how keyboards work: +-+ +-+ +-+ +-+ +-+

Ahk f1