Draw four squares of ABCD, and AD is relative. Use the method of setting one. In the first case, there are three kinds of A, the same AD and the same BC, so it is 3*2=6 kinds.

In the second case, three grids are fixed and three colors are randomly selected, so there are A33 methods. The color of the other grid is fixed, but it is divided into BC as a group and AD as a group, so it is 3*2*2= 12.

So the answer is 18 method, (you counted it wrong above)