The Max Parcel Wall Left, Right and Back are to allow walls of a maximum specified height to form. Wall will only appear if optimal grading requires them and then only to the max height.

The Building Wall settings allow for basements, crawl spaces or daylight basement configurations.

If, for example, some lot required daylight basement configurations. You would set the back wall to 10 ft. NOTE: This would also require changing the grading for the side yards to allow for return slopes up the sides.