For information regarding the credit system in WHMCS refer to this page.
Tick to enable the add funds system allowing customers to buy credit held in their account which can then be used to pay invoices. Invoices generated after credit has been added will automatically be used towards paying the balance. Both you and your customers can manually use the credit to pay invoices generated before credit was added.
The other settings define the amount a customer can add in a single transaction and the maximum limit of account credit.
Require Active Order
We recommend keeping this option ticked so clients can only add funds to their account once at least one order has been manually approved. Unticking this option can lead to an increased risk of chargebacks and fraud as malicious users can add funds - and therefore pay for products - without having to pass any fraud screening measures.
Automatic Credit Use
With this option ticked any credit on a client's account is automatically applied to the invoice as soon as it is generated. Credit added after invoice generation will not be automatically applied.
Unticking this option means no credit will be applied automatically, and needs to be manually added by staff/the client.
Credit on Downgrade
Clients will receive a credit on their account pro-rated when downgrading their package using the automated downgrade feature, when enabled.