Samsung LS21BRBAB-XAA - Manual (Page 28)

Menu Description Play/Stop
Locked
After pushing the "MENU" button more than 5 seconds, OSD
function is locked (unlocked).
Even if you use the OSD adjustment lock function, you can still
adjust MagicBright™ and Brightness and Contrast of the
monitor.
MENU
AUTO/PIP
Menu Description Play/Stop
Analog/Digital(PC) : MagicBright™
MagicBright™ is a new feature providing the optimum
viewing environment depending on the contents of the
image you are watching.
MagicBright™