Dell E1916HV 19" 16:9 LCD Monitor - Manual (Page 37)

Operating the Monitor 37
Lock Controls user access to adjustments. When Lock is selected, no
user adjustments are allowed. All keys are locked except
key.
NOTE: When the OSD is locked, pressing the menu key takes
you directly to the OSD settings menu, with 'OSD Lock' pre-
selected on entry. Press and hold
key for 6 seconds to unlock
and allow user access to all applicable settings.
Reset Menu Select this option to restore default menu settings.
Personalize Selecting this option allows you to set two shortcut keys.