I didn't explain myself well.
Seems like your shots are Bluetotth settings in Plasma. That's OK, but setting up BT in Plasma is only the first step.
The second step is to select BT device in your media player. I can't recognize any from your shots. BT device won't reproduce anything until it is selected as output channel in media player.
In SMPlayer, for example, I select BT device by hand, as shown on the shot:
VLC switches to active BT automatically. Other media players will have other means to select BT as output device.
Edit: In other words, defining Bluetooth connection in Plasma is necessary but not sufficient condition to have audio output thru Bluetooth device.
Two steps are needed for that:
- define Bluetooth connection
- select Bluetooth device in media player