Setting Hanns-G Brightness brightness

[Moffat Cafe]

Ive just got a Hanns-G HZ281HPB 27.5 Monitor and can't figure out how to adjust brightness. I press the brightness button and I see 5 things. First is a black up pointing triangle with a black down pointing triangle immediately under the up one. Second is colon, then a -/+. What this all means is a mystery to me. The mouse does nothing.

 

[MTDEW]

The adjust buttons are right beside the one you pushed on the monitor to bring that menu up. (they are just to the right of it)
All adjustments are made using the buttons on the monitor.

 

[Moffat Cafe]

Will do, thanks.
PS My wife is a mountain Dew fanatic