This switch is located at Channel>Channel Settings>Shopify Settings tab.
You can decide how the parent image location will be shown on your Shopify channel by selecting your preferred option from the dropdown menu. There are two options to choose from: At the Beginning and At the End.
If you choose “At the Beginning”, all parent images will be shown before the childrens’ images when you enter the product detail page on your Shopify Site.
If you choose “At the End”, parent images will be shown after childrens’ images on your Shopify Site.
IMPORTANT NOTE: This setting will be applied for all products in your Shopify Channel.