resize

Hi, I film everything in HD. but I want to create a smaller project (720x480). I want to use the HD footage so I can pan & zoom, but everytime I import HD footage it automatically resizes it to fit the dimensions. How do I keep the HD footage in its original size?

I followed the instructions on this page http://smallbusiness.chron.com/resize-pictures-twitter-55495.html and several alternative sources. None of these things seem to be working and the profile is 400x400 just the way it supposed to be