Credit is only for a named customer. These are the steps a sale follows when a customer buys now and pays later.
4 things it does
The till will not put a walk-in sale on credit until you name the customer
A sale to Walk-in, the anonymous customer, cannot be paid in part and cannot go on credit. The till asks you to choose or add a named customer. The payment you typed stays in the box, and the cart is kept. This rule is not a setting you can change.
Basic and Professional
A credit sale over the limit is stopped, and the screen says why
When a credit sale would take a customer past their limit, the default setting blocks it. The screen states the limit, what the customer already owes, how much room is left and how far short they are. The cart is kept as it is, with its items still in it. You can then decide how to take payment.
A credit sale over the customer's limit is stopped, and the reason is shown.Basic and Professional
A manager can approve a credit sale over the limit, with the reason kept
On the payment step, you can choose Ask a manager when a credit sale is over the limit. A reason is required. The approval never raises the customer's limit, so the next sale meets the same limit.
Basic and Professional
Take part of the money now, and the rest stays on the customer's account
Take the payment in one or more parts until the amount left is settled. Any amount still unpaid is added to the customer's account as what they owe. You cannot give change and leave a balance on the same sale, so the till never hands back cash while the customer still owes money.