Sound Issue: Sound comes from speakers,, not from headset | BO2

[_WomenBeater_]

As the title itself describes it, I have the problem that the sound only comes out of the speakers and not out of my headset. I only have the problem in BO2.
In MW3 and all other applications it works properly.
Do you have any recommendations or even know how to fix it?

[Xerxes]

Change the audio device in bo2.

[_WomenBeater_]

Xerxes I can't change it. It won't let me. I click on it and nothing happens because it's grey and "unclickable".

[Xerxes]

Its gray and unclickable because you are in game.