[Q] Get rid of default music player

Hi,

I've received my Honor 7 recently and reinstalled all my previous android applications (I used before a Nexus 4).
I use n7player for music playing but unfortunately, even if I check under "default apps / music" and select n7player, when I press play with my headphones, it's default music player witch starts.
I could not disable the application as it's in gray state. If I stop the services. music stops but If I press play again, it's again the default music player witch is starting.

Any idea?

Regards