You could be asking one of two questions, and I'm not sure which.
The other responders are thinking you mean "2-dimensional." The fix for that is to increase your levels of shading; at least four values between "lightest part" and "darkest part."
If instead you mean "the colors are just lying there," then I'm guessing you're either using straight-tube or thoroughly-mixed paints. The beauty of watercolor is in allowing pigments to mingle and mix in multiple ratios on and in the paper. Let them.