To change your service's IP address, navigate to Services --> My Services, and select the service on which you want to switch the IP address. Then, on this page, click the "Switch IP" button or the "Change" button next to the "Main IP Address." If you have multiple IP addresses on a service, please first change your IP that you want changed to your main IP address before making the request. A pop-up window will appear, asking you if you have specific requirements. As of writing this article, a regular IP change to any available IP address is a one-time fee of $3 and a change with custom requirements is a one-time fee of $5, as these have to manually be processed. In the future, as this is automated, the cost may decrease.
To make the payment, go to Billing --> My Invoices and pay the invoice referenced in the generated ticket.