You may switch your characters easily by following the steps below.

Tap on Workshop at the bottom of Game Lobby, to proceed to the workshop page, then select Character, and tap on Switch Characters located on the top left corner. Then you will be able to change to your preferred character.

If you would like to redeem more characters, you may go to the Shop >> Treasures page via Lobby, to get General Character Voucher, or use specific character vouchers to exchange for a new character.