If you need to flip the primitive to the opposite layer, such as flipping the top surface to the bottom surface, you can use the flip function.
Entrance: Layout - Flip to Opposite Side.
After selecting the element of the canvas, click the flip menu, and the element that can be flipped will be automatically flipped to the opposite layer, and will be mirrored automatically. If the element of the top layer + inner layer 1 is flipped, it will be flipped to the inner layer. 2+ ground floor.