If the balance is in Black, it means you have a credit on the card. Like if you overpaid the bill or got a refund for something you returned. When you enter a charge it will reduce (decrease) the credit you have available on it. And a payment will increase the balance.
Also make sure you have the right starting balance. If it's zero you might need to add a beginning balance for when you started the account in Quicken.
The credit card balance you OWE should be in RED. If the balance is Black then it's showing the credit card company owes you and you have a credit balance. And then when you make a payment it's like the cc owes you more. So you need to go back though your entries and find where the balance switched to black to being in your favor.
See this for more info.....