Dell P2723D 27" 1440p Monitor - Manual (Page 54)

54 │ Operating your monitor
Unlocking the OSD menu and Power buttons ：
1. Press and hold the Up or Down or Left or Right direction for four seconds.
The unlock menu appears.
2. Select the unlock icon to unlock the buttons on the display.
OSD warning messages
When the monitor does not support a particular resolution mode, the following
message is displayed:
2560x1440,
This means that the monitor cannot synchronize with the signal that it is receiving
from the computer. See
Monitor specifications for the Horizontal and Vertical
frequency ranges addressable by this monitor. Recommended mode is 2560 x
1440 .
You will see the following message before the DDC/CI function is disabled:
The function of adjusting display setting using PC application will be
Yes
No
disabled.
Do you wish to disable DDC/CI function?
You will see the following message before the Lock function is activated: