Can i seperate my Opera and game audio (they are both on Desktop audio)?

[fruitstone]

i want to play some music in the background while recording but i dont want it to be hearable on recording but my opera and minecraft are both on desktop audio and i cant figure out anything

 

[Banyarola]

Also, for some strange reason 'no audio' GIF files also end up in the Audio Mixer list while also remaining in the sources list.