My M9C board has
- one POWER LED (green) - always lit when the motherboard has power from PSU (even when computer is "OFF")
- one RESET LED (?) - I've never seen it lit (even when pressing/holding RESET button)
- four Q-LEDs - BOOT (green), VGA (white), DRAM (yellow), CPU (red) - only lit during hardware-fault conditions
- one Q-Code display - a 2-digit/8-segment numeric display (red) - always shows a 2-digit hexadecimal code (indicating the mobo is working or has halted)

These are all 2-pin/2-trace monochromatic LEDs (the Q-Code panel is 16-pin/16-trace, functionally eight 2-pin/2-trace LEDs built into one unit).
They are not 3-pin/3-trace RGB LEDs, and (as far as I can determine) they are not connected to any RGB-driving PWM controllers.

Their colours are fixed, they can't be RGB controlled. They also indicate fundamental hardware conditions, I suspect they're "hardwired" directly to the hardware ("under" user-accessible BIOS layer), I doubt they can be dimmed or disabled through firmware.

You could physically mount a colour filter (like a piece of tinted cellophane or other plastic) over the red Q-Code LEDs to change them to an apparently different colour or you could physically mount a nontransmissive screen (like a piece of black electrical tape) over them to mask them out entirely.

Blame marketing. It looks like "Multicolored" doesn't mean any LEDs with full-spectrum (RGB) capabilities, it means multiple LEDs with different (fixed) colours, lol.

Again, they're monochrome LEDs with exactly 2 pins (and 2 motherboard traces). Multicoloured/RGB LEDs need 3 or more pins (along with 3 or more traces). I'll admit it's possible that I can't see all the pins/leads - and I'm not inclined to de-solder any of my fault status LEDs to examine them more closely - and I'll admit that it's possible the motherboard uses a multi-layer PCB with (for whatever reason) 2 exposed traces and 1 or more hidden traces ... but it seems unlikely.