Hi Ohno,
after reading your other post; please post pictures when you've got everything working ... I'd be very interested in seeing this!
Coming back to your color problem, I assume you based this on the MultiColor Bouncing Balls (just adding the link here for others as a reference).
Could you post the full code here? So I can give it a try on my end.
One thing with LEDs, since you're basically are playing with only the GREEN parameter of an RGB color: The colors will look very similar, and some might not even be detectable by human eyes. Test 4 very different colors and confirm that this indeed is using different colors.
If so ... try different green variants, for example (I did not test these - but Red and Blue will have an impact on the brightness and kind-of green):
byte colors[4][3] = { {0, 0xff, 0},
{0x4D, 0x88, 0x50},
{0xD0, 0x80, 0x00},
{0x30, 0xcc ,0x30} };
just changing the GREEN parameter might not be enough to make them look different.
Let me know how this works ...