Eballas,
don't change the scale of your imported drawing. Think of all those 6ft couches around.
Rather go to the 3rd tab of the page setup dialog, there you'll find the drawing scale. That's the only field that you should modify.
You can put in any decimal value you need.
You'll think about this advice, when you combine different drawings and have no information about the drawing scale, you set 6 months ago.