Hmmm… whats the command to change language and keyboard settings?
i have en-utf8 now and everytime i write apt-get update and apt-get upgrade it`s still EN.
i have no idea if this musicbox has been translated to my language but is there way even change to Scandinavian keyboard?
I have seen pictures about dark theme musicbox how to change that?
Assuming you wamt to change the keyboard on the console you are looking for sudo dpkg-reconfigure console-data otherwise musicbox is built on a raspbian image, so just look for how to do this on Debian systems.
As for the theme I don’t know, but perhaps someone else can help 
didnt work by they way 
i guess i have to use english keyboard then
some marks like - and _ - ? / are not in the place they should be thats the problem and i dont have ä and ö letter also
Just like any guide for raspbian will tell you, use the program ‘raspi-config’ to change the language, keyboard and timezone settings.
yep i try that allready and but it missing some files…
Try installing locales. ‘apt-get install locales’