Songbook do not stop music playing when score play! And need octave tool!!

Do not stop music playing when score play!
When songbook playing, the player do not stop playing music.
This is not very convenient!

Need change score octave options in songbook!
Songbook can only change for one octave, but need more.
Some same score for different singer need this function. Only change the key still not enough for some singer.
Could you add change octave for Android app (songbook)?