Help with purchases thru Google Play..

[Hook]

Does anyone know how to switch the email address that is automatically linked to Pocket Legends when clicking "Buy" on the "Purchase Platinum" in-game screen?

I now have a different email linked to my debit card through Google Play.
Google Play is already signed in on that new email.
My Gmail is also signed on that email aswell (Don't know if that affects it, just extra info).

But for some reason when I try to buy platinum in-game, there is an automatic message stating I have insufficient funds.
But my old email is the one that appears on that screen.
I don't wish to link my bank card to my old email anymore.
I do not have an option on the screen to switch email accounts.

Keep in mind THIS IS NOT the same email I use to log in the game.
Just the email that PL automatically links to it's game purchases thru Google Play.

Any help would be appreciated