How to disable PC Master OUT

Hello guys,

When first connecting my DDJ-RX I was asked what speaker setup I'm using. Problem is I have mistakenly selected that my speakers are connected to my laptop but the truth is they are NOT, they are connected to the DDJ-RX and laptop at the same time.

If I go to Preferences - Audio I can see the Master OUT feature but the field is disabled and the button labeled Settings Utility does NOT work. What can I do?

Thanks in advance!