No sound

People ask this as

Viewers hear nothing but the streamer hears everything

This is the single most common cause: OBS has no Application Audio Capture source pointed at strAImer. See the guide "Sound", section "Where the sound plays".

Check in order

  1. Is Overall at zero? Sliders apply as you drag them — there is nothing to save. See the guide "Sound", section "The volume sliders".
  2. Is the app actually running? There is no tray icon: closing the window closes the player and quits the application.
  3. Did the sounds folder go away? If it was moved to an external drive that is now disconnected, Settings → Sound shows the path in red with "Folder is unavailable or the drive is disconnected". The default folder is used until it comes back.

Alerts specifically

Voice-over specifically