Select the wall and go to wall settings, then click "log details" just beside your override surface. You can input dimensions to your desire then ok it.
I have a question. Been struggling with this for years. Let's say I have a floor plan. But some of my rooms are on different platform levels but I need to show all related doors and windows on the single floor plan. It seems the floor plan have one single cutting plane. Wish I could control that to specific areas. Can you assist? Thank you.