QSoundEffect/SoundEffect audioDevice property has no effect when device is changed. If we set the device during the instantiation the sound is played from the given speaker device.

Attaching the sample app for your reference. When binding is checked in switch control, the audio is played only from single device irrespective of device selected but when binding is unchecked the audio is played from selected speaker device.

Note: Please make sure you have at least two speaker devices