We are having an issue of a product image we upload being way too big for the screen, it does not fit within the edges on the slideshow and at the top on the heading. I have used a tool to make the image smaller but that does not work. Does anyone know how to make the image appear much smaller so it is not in your face and fits within the height and width. I have also tried editing the 'height' and 'width' in theme liquid manually but nothing changed,
Definitely check out this article https://www.shopify.ca/partners/blog/img-url-filter
You could also add _500x500 before your file extension (filename_500x500.png) that would resize it.
A third way is to set the width/height with CSS have you tried that?
Please share your store URL and reference site URL.
So that I can check and let you know the exact solution for this.