How do I enter a credit transaction on a credit card manually?

Welcome to the QuickBooks Community, mary-glowcarwash. Let me share various details on how you can enter a credit transaction on a credit card manually in QuickBooks Online.

If you're referring to the customer's side, you can enter a sales receipt with a credit card payment. You can use this transaction if a customer asks for a refund for an item or service.

Here's how:

1. Select the + New button. Then, choose Refund receipt.
2. Click the customer's name you want to refund from the Customer dropdown list.
3. Enter the details in the fields using the same info from the original sale. 
4. In the Payment method, select a Credit card to credit back their credit card.
5. To credit back their bank account, in the Payment method, select Bank.
6. From Refund from, select which payment method and account you wish to refund the customer from.
7. Click Save and close.

If you mean for Vendor's entry, I recommend recording the credit transaction as Credit card credit. This is a payment to your liability to a credit card account that will use by a refunding vendor. Follow the steps below.

1. Select + New and select Credit card credit.
2. From the Payee field, select the appropriate vendor.
3. In the Bank/Credit account dropdown list, select the credit card to which you received the refund to.
4. Enter the Payment date, refund Amount, Tax, and Category.
5. Click Save and close.

Lastly, I'm also adding this article to further guide you in effectively managing your income and expenses using QBO: Help guide for QuickBooks Online. It contains topics about advanced accounting, banking, and payments to name a few.

Let me know if there's anything else you need help with your transactions. I'm always here to help you anytime. Take care and keep safe!