image sizes

I see in config where to change the thumb sizes,, also where to change the "full size" of the image.
The problem is that the image used on the individual "product page" is using the thumb.. and that's too small for such a large area.

What I want is: 175px for thumbs, 300px for product page, and 600px for the "full size" when you click the image on the product page.

Can this be done?

OK thanks,

I tried it, but it only worked in one situation and not another.

When I made the change (using 300px in the config and 175px in the menu option) to the "products" menu item it worked:
see here: wideawake.us.cloudlogin.co/index.php/hika-shop
BUT
when i did the same thing to a test menu item for "categories".. It only effect the "category icons", but not the thumbs of the products below.
see here: wideawake.us.cloudlogin.co/index.php/videos

I thought possibly it was a cache issue,, but I tried clearing the cache and nothing has changed yet. In fact I turned Joomla caching off and still no change.