Samsung LS24HUCEFV-XAA - Manual (Page 41)

Menu Description
Brightness When OSD is not on the screen, push the button to adjust brightness.
SOURCE
Menu Description
SOURCE
Selects the input signal while the OSD is off.
(When the source button is pressed to change the input mode, a message
appears in the upper left of the screen displaying the current mode -- PC, DVI,
AV, S-Video and , Component and HDMI input signal.)
Changing the source is only allowed for external devices that are connected to the
monitor at the time.