Thank you for the advice.  The ceiling is vaulted, and I have tried both raising and lowering it. I must be missing something very basic, since the ceiling and roof are not behaving like I expected.  I am not sure what is controlling the roof height.
 
	 
 
	Here is a 120" ceiling structure and the elevation, and the walls still show
 
	
 
	 
 
	followed by a 72" ceiling and elevation, and the walls disappear, but the porch beams/soffits are still the same:
 
	
 
	 
 
	For the 6ft structure, the walls have disappeared, but the porch ceiling is much higher than 6'.  It does not change even at 120"