Dell UP3214Q Monitor - Manual (Page 47)

Operating the Monitor  47
3. Press and hold the button for approximately 8 sec.
4. The DisplayPort configuration message will appear:
DisplayPort 1.2?
Dell UP3214Q
Enable
Disable
5. Use the button to enable DP1.2 or button to exit without making any
changes.
Repeat the above steps to change the setting back to DP 1.1a if necessary.