If you recently installed OBS and the sound isn't playing on the livestreams the problem may not be a problem after all. Before you start tinkering and changing settings, just restart. This will usually make everything work as it should.
One quick way you can tell if you're settings are fine and you just need a reboot is to hit record and play some audio on your desktop and do a mic test.
If the mic and background sound show up find in the recording.
Restart and then go live again and see if the sound plays on the livestream. I suspect it will.
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