How to configure a different standard language than the base language for CRM endusers? (oversteer personal settings?)

Hi, I'm implementing my first Dynamics CRM project. The newly created CRM instance has "English" as a base language. I already installed the "German" language pack and I know where to change the language for my personal user. What's a good practice to enable "German" as the primary CRM language for endusers? 

I read that the base language can't be changed after the CRM instance was created, is there a way to still e.g. oversteer the personal settings to an already installed language pack?

Kind regards,

Mario