How to display pictures larger?

How can I change the size of the pictures that are displayed with the products? See cmathletics.com/demo

Thanks!

For the images on the product page, you need to go in the tab "Files" of the configuration and change the "thumbnails width/height" options.
For the images on the products listings, you need to go in the products listings modules/menus options via the menu Display->Content modules/menus and change the "images width/height" options.

OK, I tried this. I have one product that is using characteristics. It is at cmathletics.com/demo . Click on Men's Apparel. The very first product called Seasons - Crew is what you should click on. You will see that the thumbnails, etc. are all one size. They also fit in the upper area. When you change the size to something else (like medium or large) the thumbnails get larger and they overlap the bottom section. How do I fix this and prevent it from happening?

One other question: When selecting a characteristic, it displays that at the top like this: Seasons - Crew: Small. Is there a way to take the ":Small" out of there? If so, where?

Thanks!

I see that you add the CSS:
.hikashop_child_image_big {
height: 60px;
}

in your template.css file. However, that CSS is only for the default images.
For the images once the variant is changed, you should use the CSS:

.hikashop_child_image {
height: 60px !important;
}