Hello,
You forget to provide FTP access. Meanwhile, we do not see the problem on your site – https://gyazo.com/d13d85e3725a3a0e86e0693333169ecf Clear cache and check one more time.
About image size read here – https://xstore.helpscoutdocs.com/article/89-product-images It is recommended to use a graphics editor and prepare product images (make them the same size) before uploading images to your media gallery.
Regards
