Credit Check Credit Hold

I need to know the correct setting to use for customers with a credit balance, so their orders can go through without a credit check if the order amount is less than on-accunt balance. Scenario 1: Customer A has a on-account balance of $10,000.00 in his account and orders goods worth $9000.00. The sales order should go through without a credit check/hold. Scenario 2: Customer B has on-account balance of $5000.00 in his account and orders goods worth $6000.00. The sales order should be on hold until additional money is added or the order is adjusted to be within the balance.