Piano sound very low

Hello,

I've an issue with android App.
When I play a song, piano is very quiet/low, even if tablet sound is set to max.
i dont have this issue with other instruments, only piano.
Android sound is set to max, when I play in anyothers app (VLC for instance, it's ok).
I've tried to opened mixer setting in Musescore to find a solution but there's no option about piano.

Any ideas ?

Best regards