Dell 1708FP User Manual page 11

NOTE: If locked in the down position,
1. Push the monitor down,
2. Press the Lock down / release button on the bottom rear of stand to unlock the monitor.
3. Lift the monitor up and extend the stand to the desired height.
NOTICE: Before relocating or moving the monitor to a different location, make sure that the stand is LOCKED DOWN. To lock it down, lower the height of the panel until it clicks
and is locked into place.