We would like to increase the size of the product images on both category pages and on product detail pages. Problem is that we do not know how to do this.
We do know we can increase the size of the product image in the category listing by choosing "Product layout: Big images". Problem is that then only 2 items are positioned next to eachother on desktops and only 1 on a mobile device. We would like to have 4 and 2 respectively. That is why we now have chosen for "Product layout: Only important information" which does just that. But now the product images are only 120x120px in the product listing and smaller than the desired 600x600px on the product detail page.
I understood the size of product images are set in"Media | Settings | Thumbnail size". In the Media setting it is indicated that the thumbnails would be 200x200px for value  items (product listing) and 600x600px for value  items (product detail page). So I expected our product images to be these sizes. But now they are not and I do not understand why. So I hope somebody can learn me how to get the product images larger under the given circumstances?
Thank you very much!