How to change default sorting of a collection
Our app automatically renders the default sorting order from your Shopify data so the sorting order of a collection always displays as how it is organized in the Shopify collection.
You can change the Shopify default sorting of a collection within a few steps.
If you select Manually, then you can click and drag the products on the list to reorder them. You can also reorder in bulk by selecting many products and click Move. This Manually option will be displayed as Featured on the frontend.
For Best selling sorting, because Shopify doesn't return Best Selling ranking like other sorting types and requires us to get it by metafield, instead. To make it works, please follow this guide.