BigCommerce site: Assign Template Layout File to product pages

We have special Template Layout Files that have custom headers for each type of product in our store. This project is to change the Template Layout File for 350 products. In BigCommerce control panel: Go to: Edit product -> Other Details: Scroll down to Template Layout File and change that file as follows: To change the template on product pages, you have to manually change it on each product to for example, [login to view URL] There is not a way to do this by importation - I have already checked that and confirmed there is no way to do this by product import ONLY CHANGE THE TEMPLATE LAYOUT FILE IF IT IS CURRENTLY: [login to view URL] Cards-USB-WiFi For all the products in this category and its subcategories (except Ubiquiti and MikroTik cards): [login to view URL] change the template layout file to: [login to view URL] For all the products in this category and its subcategories: [login to view URL] change the template layout file to [login to view URL] Make sure that brand nname is set to MikroTik (this setting is right next to the setting for template layout file, in the Other Details tab - see attachment) For all the products in this category and its subcategories: [login to view URL] change the template layout file to [login to view URL] Make sure that brand nname is set to Ubiquiti Networks (this setting is right next to the setting for template layout file, in the Other Details tab- see attachment) Power Supplies, Adapters: For all the products in this category and its subcategories: [login to view URL] change the template layout file to [login to view URL] See attached graphic of where you change the template layout file in the BigCommerce control panel