The type of billing associated with an account determines how credits are processed.
For accounts with a 7-digit invoice number (1231234), credits are not automatically applied. If you need to apply credits to an open invoice, you can make the request through email, phone, or by remittance.
On the other hand, if the invoice number is alphanumeric and starts with a letter (AWU150), it is associated with a statement or prepaid account. Credits for these accounts are automatically applied to the balance, whether it is a credit or an amount due.