Play/ pause button to automatically launch Spotify instead of iTunes / altering key connection

Hi all,

There's something I've tried to figure out, but I can't seem to resolve it. On the keyboard of the MacBook there are 'music' keys (back, pause/play, forward), in my version those are on F7, F8, F9.

As for the F8 pause/ play button, it automatically launches iTunes. A nice system, I guess. But... I very rarely use iTunes. And I use Spotify all the time.

When I'm listening through Spotify, it does control Spotify (pausing or resuming a song), but when I've not listened for a while (even though Spotify is still active! I did not shut down the program) and I press play/ resume, it launches iTunes. So it seems that iTunes is the dominant connection. While much rather, I'd want to have this key to always control Spotify (launching it, play/resuming and so on). So the question is, is there a way to link this key to Spotify rather than iTunes?

Thanks for your insights! :)