Yellow means there has been an overpayment.  If you click the Payment Details button (screenshot #1) you can move the patient payment to the deposit account (screenshot #2). This will allow you to post the payment from insurance.  Please note, the Post button will remain grayed out until the overpayment has been moved to the deposit account.

Green means you can post the insurance payment as you normally would.  You could also post a client payment from the deposit account if there is an available balance.