Board Thread:Questions and Answers/@comment-83.40.194.123-20160516202638/@comment-5872251-20160516205448

http://ensemble-stars.wikia.com/wiki/Ensemble_Stars!_Master_Guide#How_to_transfer_Game_Data_to_another_Phone

So basically, you put in the code after tapping the red button (Model Change). Keep in mind that you wont be able to immediately switch accounts again, until after a day has passed.