Go to the Playback tab and you'll find the old Windows Sound Controls. You should see the old-fashioned sound control panel pop up where you can select which action plays which windows sound.
If you want to disable exclusive control, you have to do it in the old windows sound settings, there is no other way to toggle this (as far as I am aware): Right-click the speaker icon in your taskbar, and select 'Sounds'. However, this will sometimes make VoiceMeeter lose your output, because OBS still takes exclusive control. However, if you use VoiceMeeter's MME mode, it will work at the cost of higher latency than WDM mode. If you use Audio monitoring on a device that's selected within VoiceMeeter as an output in WDM mode, it won't work properly, because both OBS and VoiceMeeter want exclusive control. I'm still posting this here because more people will probably want a workaround for it and it's kinda convoluted to get it to work consistently, especially with Windows 10 hiding more and more options in their fancy new Settings windows. So I've been forever struggling to get audio monitoring to work properly, and the problem has partly been VoiceMeeter.