I'm using the Porto theme. On the demo version's product page the main product image changes when you click on a variant. For some reason I cannot get this to happen on mine. I've tried every setting I could think of and even created a new test product to attempt to start fresh. Regardless of the image I assign to each variant, or what settings I set in the theme including the swatches settings, the picture never changes when you click a variant. I also uploaded a fresh unpublished version of the Porto theme to see if it worked there, and it did not.
I sell decals and have photos of each color choice. I would like for the appropriate colored image to show when a buyer clicks on the color variant. Here is an example of their demo. When you click a color, it changes the image. https://porto-demo6-new.myshopify.com/products/dna-on-ear-headphones?variant=12520364245047
Please let me know what I'm missing!
Thank you for your question.
Please share your store URL, page URL and also password (if your store has one), I'll help you out to the best of my ability.