Klarna

Hi,
i am trying to activate klarna for stripe. While in test mode it works fine but when i change the mode to live..
i get an error 'An error occurred while processing the card. Try again later or with a different payment method.'

Moreover is there any way to change available options for klarna i.e. we only like to implement paynow and paylater.

At the moment there is a third option pay in installments is also available which we would like to remove.