LG 42PA4500 Owner's Manual page 173

✎ While viewing an external device, these cases may result in image burn:
- a video with stationary caption (such as network name)
- 4 : 3 aspect ratio mode for an extended period
Take caution when using these functions.
✎ Available picture size may differ depending on the input signal.
✎ At HDMI/RGB-PC input, select the image ratios of 4:3 and 16:9.
(Only for models supporting PC connection)