Certain apps are in a different language?

I have just bought the iPhones 5s and I've started downloading different apps, and most of them are in danish/english (like they're supposed to be), but certain apps are in french? Facebook, Youtube and Instagram are all in danish, but Snapchat, Tumblr, and Spotify are all in french.

I have tried signing out of the app store and in again, and I have also checked my language settings, and they are all set to danish.

So why are some of my apps in french?