Changing from subdomain to primary domain

I’ve got a site we setup on a subdomain while testing and finishing everything up. Now that the site is ready I’ve changed it so the domain points to that directory. The problem I’m having is that now that I’ve changed it over my checkout & cart are not loading. I know it’s a setting I’ve missed somewhere but I can’t figure out what I need to change. I can click “add to cart” and it shows at the top right the new amount under “My Cart”. But as soon as I click on checkout it just reloads the page and the cart goes to $0.