In the template files, open the content-al_product.php file.
Edit line 22 from this: jQuery(".a-product-image").colorbox({transition: 'elastic', initialWidth: 200});
Change it to this: jQuery(".a-product-image").colorbox({transition: 'elastic', initialWidth: 200, scalePhotos: true, maxHeight: '95%'});
Really needed this and hope it will help someone else.