Hi there, @TS45. You can easily correct an incorrectly categorized transaction in the Posted Tab under the Bank transactions section. Simply click the category listed in the Match/Category column, then select the appropriate income account from the dropdown menu or type to search for it.

Your changes will be saved automatically once you select the correct category.
Additionally, you can check out this helpful article on how to properly categorize your future transactions: Categorize online bank transactions in QuickBooks Online.
You’re always welcome to reach out if you have any further questions or concerns.