Wall default height not changing

[UpTheAggan]

I am designing a barn, and have selected "Garage" for room type to eliminate the automatic insertion of a wood platform floor. It is concrete slab. My interior posts and top beams are 168" above the floor, and perspective shows the beams sticking out horizontally through the roof. The reason: the exterior walls are too low. Interior camera on panelling shows three sheets of plywood high, which is 144". I have changed the default value for 1st and second floor rooms to be 168". The exterior walls have not changed to that height even though for each, "Structure" lists the grayed-out "default value" (which means I cannot change it on that window). I have run out of ways to fool CA Pro into increasing my wall heights further.

What am I missing?