How can I change credit card payment from being registered as income to an expense?

I can see you're struggling to manage your banking transactions, @Argos. Let me help you fix the credit card payment that shows as income in your QuickBooks Self-Employed.

Before that, did you connect to your bank through online banking? If you have, please be aware that we rely on the information shared by your bank.

On the other hand, if you import them through a CSV file, this will also depend on how you map your banking transaction. If you want to change it type and category, here's how to modify them manually:

1. Locate the transaction from the Transaction tab.
2. Click the Credit Card Payment from the Category column.
3. After that, a small screen will appear that contains different categories.
4. Next, change the type by clicking the Transfer, then choose Business or Personal.

Optionally, you want to exclude all the transactions and re-import them again. 

I'm also adding this article for your guide on handling your banking transaction in QuickBooks Self-employed:

• Categorize money transfers in QuickBooks Self-Employed
• Categorize transactions in QuickBooks Self-Employed
• Schedule C and expense categories in QuickBooks Self-Employed

Let me know if you still have issues or queries with your credit card payment; you can always add your comment below. Have a nice day.