If you are using an audio interface, plug your headphones into your audio interface. In FarPlay’s main window, go to the Devices section and make sure the Headphones pull-down menu is set to your audio interface.

If you aren’t using an audio interface, go to FarPlay’s main window. In the Devices section, make sure the Headphones pull-down menu is set to your headphones (possibly listed as ‘External Headphones’ or listed using the name of your sound card).