Haier L42T1 Owner's Manual page 27

Lock Setup
Preset Source
Preset source is opted for setting up start source.
Press VOL+/- button to select Off, TV, AV1,AV2,S-Video,YPbPr/YCbCr, PC, HDMI1, HDMI2
and USB in turn.
UnLock
Press CH+/- button to select Unlock mode. Press VOL+/- button to unlock all
set modes, setting all lock options to off.
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