Selecting the WooGallery layout from the Edit product page is pretty simple. Follow the steps below to do it: 

1) First, go to the Products > All Products page from your dashboard. 

2) Then select a product you want to Edit. 

3) In the Edit product page, you will find the WooGallery Settings as a screen element in the sidebar.

4) Now, select a layout you created from the dropdown and Update the product. Go to the product page and refresh it to see the changes.