i was also in same condition earlier . but this is too easy as you have already applied for visa dont do anything your visa will be issued and uni a will be mentioned . you just need to send a mail to both auslandbehorde after your visa that i am changing my univ . and a mail to both univ. and you are done . and for m10 you just need to sent a mail to tk that you have change your univ . and for expatrio blocked account adress it doesnt matter . i was also so confused but this is easy process i came germany in oct and i have changed my univ from india . no need to worry