LG 55LX9500 Owner's Manual page 41

Screen Reset (Reset to original initial values)
Returns Position, Size, and Phase to the default initial settings.
This feature operates only in RGB-PC mode.
1
Select PICTURE.
MENU
2
Select Screen (RGB-PC).
ENTER
3
Select Reset.
ENTER
4
Select Yes.
ENTER
5
Start Reset.
ENTER
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