In your Shift4Shop Online Store Manager, you will find a series of Shipping Settings that can be found by going to Settings > Shipping and then clicking on the Enter Settings button under the "Carrier Settings" section.
Once there, click on the + Icon next to "Shipping Settings to reveal a series of checkboxes. Within this area, you will see a checkbox titled "Preview all shipping methods."
In a previous guide (located here), we described the basic function of your Shift4Shop Store's Shipping Preview option. The "Preview all shipping methods" setting described here will work in conjunction with the Shipping Preview option by allowing you to dictate if all shipping methods are previewed or if you'd like to have only one shown to your shoppers.
When set to "Preview all shipping methods," all of the order's applicable shipping methods on your store will be displayed.
If you elect not to show all shipping methods in the preview (by removing the check mark from the box), then the preview will display the cheapest rate for your shipping services.