Dell S2425HS User Manual page 54

Use the joystick to lock the button(s).
Press the left directional navigation of joystick for four seconds, a menu appears on the
screen.
Select one of the following options:
Options
1
Menu Button lock
2
Power Button lock
3
Menu and Power Button lock
54 | Operating the monitor
Select Option:
Description
Select this option to lock the OSD menu function.
Use this option to lock the power button. It
prevents the user to turn off the monitor using the
power button.
Use this option to lock the OSD menu and power
button to turn off the monitor.