The preferred shipping method for an order is based on:
Shoppers can always select a different shipping method and a different carrier, if available. You can display the Shipping Estimator on your site to help customers choose a shipping carrier.
Default Shipping Carrier
If you have shipping accounts with UPS, as well as FedEx, USPS, or other carriers, you can select a default shipping carrier for your NetSuite account. NetSuite shows the default carrier to Commerce web store shoppers if other preferences or customer address information cannot be used to determine an appropriate shipping method. Set this preference if you want to preselect a carrier for your shoppers when no other preference settings apply.
For more information about creating a default shipping carrier in NetSuite, see the help topic Selecting a Default Shipping Carrier.
Default Web Site Shipping Method
The Default Web Site Shipping Method is the preferred shipping carrier displayed in Checkout. Set this preference if you want customers to see this shipping method first when checking out. You can select a default shipping method for your web site whether you use multiple carriers or not.
To select a default shipping method for a web site:
Go to Setup > SuiteCommerce Advanced > Set Up Web Site..
If you use the Multiple Web Sites feature, click Edit next to the web site you want to modify.
On the Shopping subtab, in the Shipping Page section, select a shipping method in the Default Web Site Shipping Method field.
If a shopper placed a previous order through your website, the customer record stores the shipping method selected for the last order. This information updates each time the customer selects a shipping method on the order form. The shopper's previous shipping method choice is preselected in Checkout.