How to bound the designed interior entities to the building

Note: if you don’t bind the entities to the building floor,  the entities can't be selected or hidden together with the building, and the entities may appear at the height you showed before if you use the Show Floor command to open another floor.

ANSWER： Click the button next to the "Floor properties" option in the Properties window, select the floor to be bound in the pop-up "Floor Properties" dialog box, and click "Define floor" button to bind all the interior entities (don’t need to select all of them) to the corresponding floor.

If press the SHIFT key, you can bind the interior entities to the multiple floors you select.