TV's "info" button reports Source HDMI/DVI as 720x480/60p. Is this the resolution? This TV is supposed to get 1080p, 120 refresh rate. How do I adjust this? Has TV been set up wrong? Input is AT&T U-Verse with HD option. HDMI cable is a high speed with ethernet 3D. TV is a Brand New (today) Samsung un40d6400. Thanks for any help!