How do I retrieve accounts from old device to a new device?

As long as you have bound the game to an external account (IM30 is best) then when you start a new game on the new device, as soon as you are able to access the settings menu (you need to go through a bit of tutorial first) go to the Account option and choose switch account. You can then log in with the IM30 account details that the old game is bound to and it will let you return to it.