Images not optimising for mobile, configuration of images on product pages

Hello

I have three separate issues:

  1. Image reconfiguring on product page - right now, my images appear full-size and are stacked on top of each other vertically. How can I change the configuration of images so there is one main image appearing and thumbnails beneath it to move through the images?

  2. On mobile view, on each product page the images appear first with the title/text/price details at the bottom. I would like the title/text/price about the productt to appear above the images. How can I achieve this on mobile view?

  3. I just added a new product to my website. I am using the same template and details as previous products I have created and I have sized the images the same as previous products. The previous products appear perfectly when viewed on desktop or mobile. However, the new product is appearing differently - it is fine on desktop but very/too large on mobile view. Can someone explain why the optimisation may have suddenly changed when adding a new product?