I have products that vary from 5oz to 13oz. When a customer purchases more than one, it'll of course weigh at, or more, than 16oz, shifting the USPS shipping option to Priority mail.
How can I set my shipping settings to automatically show that as their shipping option, instead of them having the option to ship Economy? I am losing money because of shipping.
One of the methods you can try is to set the rates "based on item weight" condition so that, when the customer orders more than the specified weight, a flat rate shows up. In your case, you can check out the USPS Priority rates for different location and add a flat rate that is almost accurate. You can create shipping zones for the areas you ship and add similar condition for these zones.
In order to set up carrier calculated rates based on conditions, you will have to use an app that helps you choose a specific service for a weight-based condition. For example, with our app, Multi Carrier Shipping Label app, you can create a condition for a specific weight range (say 16 oz and more). For this condition, you can select only the required USPS service to display at the checkout. You can also check out other apps here.
I hope this helps!