Hi egertler,
Thank you for contacting the Community.
Can I ask whether you have the credit card in question connected on the banking screen?
If not you will have change the transactions manually. You can do this by clicking the Accounting tab on the left hand side and then Chart of Accounts at the top of the screen. Find the Credit Card and click Account History. You can then click onto the transactions and select Edit. This will open the transaction and you can change the account/s.
Please let me know if there is anything else I can help with. :)