press these buttons to change the RGB colors of the layers:

back layer:

1 = minus in R

2 = plus in R

3 = minus in G

4 = plus in G

5 = minus in B

6 = plus in B

mid layer:

Q = minus in R

W = plus in R

E = minus in G

R = plus in G

T = minus in B

Y = plus in B

mid layer:

A = minus in R

S = plus in R

D = minus in G

F = plus in G

G = minus in B

H = plus in B