Review some of your pictures while you read this. Most likely the Night Portrait Mode of the camera was used and camera was handheld when the picture was taken. In this mode, a slow shutter speed is used with flash to obtain better ambient-lit background detail. If you are holding the camera while shooting, any camera movement will cause background detail, especially lights, to look steaked. For better results, use tripod and the camera’s selftimer to take the shot.