To transfer your account between different OS, please follow the steps below:

Current Device:
1.) Open the Menu in the Home screen, then go to [Account Transfer] → [Transfer to different OS].
2.) Enter a password, then select [Password Settings].
3.) Either take a screenshot of the newly generated Transfer ID, or write it down somewhere. Make sure not to lose it, and don't share it with anyone else!

New Device:
1.) On the title screen, tap the button on the upper right corner, then select [Account Transfer] → [Transfer to different OS].
2.) Enter the Transfer ID and password created on your previous device, then select [Transfer].
3.) Double check the player name and rank displayed on the screen, then select [Account Transfer] if it is the correct account.