Once your custom domain is activated, you just need to edit your individual Kartra Pages (or Memberships, Checkout pages, Video pages, etc.) in order to switch them from being hosted in Kartra to your domain.
When you publish a page, the system will prompt the default Kartra-hosted link. Simply click on the EDIT button to modify it:
Finally, select your domain in the dropdown, type your desired page name, and click the SAVE button. So, in the example below, the page will be hosted at https://YourDomain.com/sales: