I have a BJ 26 BL and I adjust the outdrive by loosening the set screws on the outdrive unit on the side of the mount.  Remember just like a full size boat prop in = aft up, bow down; prop out = bow up, aft down.  The more boat out of the water the faster it will go, however as you increase the prop angle out, the boat will start to "porpoise" i. e the bow will bounce up and down and/or if you are going fast enough the boat will flip end over end out of the water.  In a full size boat this can be deadly, for r/c boats it usually means either get in the fetch boat or go swimming.