If you have already added new Gelato products to your BigCommerce store or if you connected existing products or variants to Gelato, the retail price can be only updated from your BigCommerce store.
You are also able to bulk edit multiple products at the same time. You can read more about editing products in BigCommerce's Help Center article Editing Products.

Currently, it is not possible to change the retail price of your BigCommerce products from Gelato.