Thanks for sharing your concern in the Community space. I can provide information on how to change transaction from expense to income.
If this is manually recorded in QuickBooks, you'll need to delete it and create a new sales transaction. There's just a few steps to do that:
Go to the Expenses tab.
Find the transaction that you want to correct. It may be a Bill, Check, Expense, or Credit Card transaction.
Click the drop-down arrow beside View/Edit.
Click Yes to confirm.
Once done, enter a sales transaction to categorize as income. For reimbursable transactions, you'll need to create a billable expense which is only available in QuickBooks Online Plus.
Create an expense transaction on the Bill, Expense, or Check window as usual.
Enter all necessary information.
Check the box under Billable column. If the Billable checkbox does not appear, you have not yet set up billable expense tracking.
Make sure to select the customer to be billed for the expense from the Customer/Project drop-down column.
Click Save and close.
That should get you going with re-categorizing your expense transaction. Please let me know how this goes by leaving a comment below if you have other questions. I'd be happy to help in any way I can. Have a cheerful day.