Product Images Problem.? All images are Large?

Hello Friends,
i have 200 products in my website, and for them . i have uploaded my all images to /images folder. but when i go to my website and open the product page, my product main image is good. and in the bottom more images for my product are resized to 64x64, but when i save that thumbnail image, it size is 400x400.
i am using two kind of images.
image.jpg
image_01.jpg

I want in my website all small images should be 64x64 and size around some kb, when some one click on it then large image open 400x400 pixles. and product main image should be also 400x400pixles for faster loading my website.

here is my website.

Please help.

https://www.3drevolution.org

all images are 400 x 400 , zencart with scale them but wont compress them . so you end up with same kb .

you can follow the tutorial on how to add image to your shop

small , medium , large and for additional image ..

now i dont need it, i have installed image handler for my website. and its working great. my website is loading faster. Please check it and tell me how is it? https://www.3drevolution.org thanks for your comments.