I have 7.0, so it may be different, but...
Start a new project, or remove all the video files from your current one. For whatever reason, the changes you make only apply to clips imported after you change your settings.
Up at the top, click on project > project settings > general
In the "video" box, check the box that says "Scale clips to project dimensions..."
Import the clips again and they should be the right size.
Hope it helps.