Where is the question mark switch on super Mario 64 DS?

right when you enter the castle you will see the sun painting on the ground. When the sun is shining on it press X.ONLY ON STANDERD MODE. Then look up and you will be in a rainbow room. Hit the swith, save, and whalla!!! YOU NOW HAVE ALL RED BLOCKS SOLID!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! right when you enter the castle you will see the sun painting on the ground. When the sun is shining on it press X.ONLY ON STANDERD MODE. Then look up and you will be in a rainbow room. Hit the swith, save, and whalla!!! YOU NOW HAVE ALL RED BLOCKS SOLID!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!