Hello Dear, regarding the question at 11:30 I believe the answer was right you just have to quick select every object on that layer and then set them to by layer (by going to the properties panel) no matter what each object's color was, you can set them to be by layer and they will become the same color of that layer. You just used a block and that is wrong in order to change the color of that block you will have to go to the block editor in order to be able to change the color of that block, best regards.
