If your source is HD make sure that it is set to output in HD.
The source has to be connected with HDMI in most cases.
The channel and the content have to be in HD. The TV indicates the resolution of the source. The TV will upscale content to the native resolution of the panel.
If you are watching an old movie originally shot in 480, that's what u gonna get, there is no magic. Some TVs there is a RESIZE button and you can have the 480 image fill up your entire 1080 screen but the quality is not going to magically improve.
If your source is HD make sure that it is set to output in HD.
The source has to be connected with HDMI in most cases.
The channel and the content have to be in HD. The TV indicates the resolution of the source. The TV will upscale content to the native resolution of the panel.