This warning will always show in Preferences > Payments > [payment method name] for any payment methods which require your site to be secure. It is a generic warning and will display even if you have set up in-store credit card processing. If you have not yet set up in-store credit card processing and wish to have your customers pay via credit card directly on your site, please open a ticket in the support portal
. This will need to be in place before the payment gateway will work on your site.