Samsung 920XT manual MENU button, MagicBright

MENU button

Menu	Description
	This is the function that locks the OSD in order to keep the current states of
	settings or prevent others from adjusting the current settings.
	Lock : Hold down the menu button for more than five (5) seconds to activate the
	OSD adjustment lock function.
OSD Lock & Unlock	Unlock : Hold down the menu button for more than five (5) seconds to
	deactivate the OSD adjustment lock function.
	Though the OSD adjustment lock function is activated, you can still adjust
	the brightness and contrast, and adjust MagicBright ( ) using the Direct
	button.
MagicBright™