External Screen with speakers - Turn down volume!

[habber]

Hello.
I just bought a External screen for my 2013 macbook pro.
The screen have great speakers that i would like to use. But when connected with HDMI i can't use my keyboard to turn down the volume, i need to use the buttons on the screen. Are there any way to make this possible? Maybe an application or something?

Screen: ASUS MX299Q 29-Inch Ultra Wide LED-Lit Monitor

Hope someone can help me, it is getting kinda frustrating

 

[nicxx]

Try this, BetterTouchTool: http://www.boastr.de

With BTT you are able to map all kinds of software functionality to your keyboard.

 

[habber]

The problem is that i can only use the buttons on the screen to control the volume, and it doesn't seem that there are any driver software for OSX where i can seem to control the volume from the software, rather than the hardware buttons on the screen