Samsung SyncMaster 550DX User Manual page 74

PIP
Basic information required to adjust PIP will appear in the menu screen.
PIP will be disabled when Video Wall is ON.
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Note that Picture Size is disabled when PIP is ON.
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PIP Size
View the PIP Size of the current display.
PIP Source
Select a PIP input source.
Sound Select
Select and enable the sound from either the primary screen or secondary screen.
Channel
The channel can be changed if PIP Source is TV.