How to make media keys control media player? Spotify

How do make media keys control media player like Spotify or SoundCloud (SoundCleod)?

When playing music, I push pause when my phone rings and music continues to play and iTunes opens. It used to work but not appears the media keys are broken.

Or if you're cruising facebook (safari), want to watch a video so you hit media key pause play. The music keeps playing but the video on facebook pauses. Again this used to work, but now is broken.

Mac Mojave

Cant listen to music at work now as I cant quickly pause it when the phone rings. Any help would be great. Thanks