Playing via Bluetooth is quite simple most of the time. Go to the "Bluetooth settings" and select the device to send the music to.
However, currently I am in the following situation (also after reboot):
I am connected to the speakers which I test successfully in "Settings, Sound" (Front left and right). But when I play some music via the Firefox browser, the sound is still on my laptop and not the external device.
How can I use the external device for audio?
If the correct device is already highlighted under Settings > Sound > Output, try selecting a different device then the desired device.
I'm having the same problem but couldn't find a workaround other than this.