When I re-stain my cedar shingles with a different color?

Cedar is a very soft wood and when you go pressure washing it you will see that there will be no way to get down far enough to remove the old color. This comes from me having western red cedar and trying to seal it with a color sealant. It looked good for 2 years then my troubles began. The side that got the full sun exposure turned lighter than the back and when trying to redo it had a two tone effect. Big mistake on my part. Just have to live with it now. To bad 10.000 dollars worth of cedar and I have to live with what I done. I was trying to keep it from turning that gray color. Long live experience.