Thanks everyone.
mgabriel - I made the second floor by dragging walls but every time I do this and draw a wall over the garage, the garage wall height increases to same height as the first floor.
dshall - sorry I was not more clear on what I ultimately want. If you look at the first picture (the one without the second floor). you notice about two siding panels above the garage doors. the garage wall height is also lower than the first floor of my house. I want this garage wall to stay at this height when I add the second floor. Now if you look at the second picture after I have built my second floor, the garage wall height has increased. Initially (picture one) their were two siding panels above the garage now their are eight (the garage walls have defaulted to the same height as the rest of the main floor.
Ultimately what I want is to lower the walls back to what they were in picture one.
Hope that made sense. I have tried playing with stem walls and floor heights but when I does not change the height of my garage walls.
Thanks for your time on this guys.