If you see a patient has a credit balance on one claim and a balance on a later claim, you can easily move the overpayment/credit to the later claim with a balance. 

Select the "Credit Transfer" button which will only show on claims where there exists a credit balance.

On the window that pops-up, you can then follow the instructions:

At the top select the claim to transfer credit FROM, then adjust the credit amount if you only want to transfer a portion, or leave as the full amount. 

Select the Reason code/Credit code and then select the claim to transfer the credit TO.

Remember to select the "Save" button at the bottom to save the transaction.