I am not sure if QB online receive payments screen is the same as my version. In my version of QB when posting a customer payment in the receive payments window and there is a miscellaneous difference, I use the "button" at the top that is marked "discounts and credits". A two tab box comes up, using the tab marked "discount" just put in the miscellaneous difference amount and choose an account to post it to (I use miscellaneous). I hope this helps you.
