Changing focal point on Canon Rebel

I have a Canon Rebel. It has the typical cross of focal points in the viewfinder. It used to only auto focus on one of the points in the camera, which was very good because I could be guaranteed to use that one point, focus and then move the camera to capture the frame that I wanted. Now it suddenly is using all of the focal points and I cant seem to focus on one particular area (like the eyes) anymore. I'm doing a portrait and it wants to focus on the nose, or the ear. How do I fix this? How do I get it only to use one of the focal point sensors? Any suggestions would be greeeeatly appreciated.

Thanks,
James