Roof/Wall Height

[JoyA]

I'd appreciate anyone who can help me here - I'm a somewhat experienced amateur user, using Home Designer Interiors 2014, but I cannot figure out how to fix the roof over one room. I'll let the pictures show the problem:



The second floor part where the roof is lowered is all one room. The snowy picture is the back side of the house. Here are pictures of the inside:



So the wall heights are all different. What do I need to change to bring the roof down?

And obviously there are other problems, like that the garage is floating above the ground, I'll deal with that, but I cannot figure out this roof thing...

Thank you in advance.