I am doing challenge 2 in the junior programmer course, where the player is spawning the ball instead of the dog, but needs to be spawning the dog. The answer seems to be to go into the inspector for PlayerControllerX and make sure that the dog prefab asset is assigned instead of the ball, but when I do this, the player still spawns the ball.
It does have a note that says default references will only be applied in edit mode. But it seems like everyone online has only had to switch out the prefabs for it to work.