Rule 112.2 · Spells
A spell’s owner is the same as the owner of the card that represents it, unless it’s a copy. In that case, the owner of the spell is the player under whose control it was put on the stack. A spell’s controller is, by default, the player who put it on the stack. Every spell has a controller.
Subrules
Some effects instruct a player to create a copy of a card and say they may cast it. In that case, the owner of that copy is the player who is instructed to create it and given permission to cast it.