In the Details > Summary tab of the original job, select the Include: Change Orders and Include: Linked Change Orders check boxes to include change order values in your job breakdown table.
Outside of the US, 'change orders' are called 'variations'. Learn more in About Variation Costs.
In order to view content or perform actions referred to in this article you need to have the appropriate permissions enabled in your security group. Go to System > Setup > Security Groups and access your security group to update your permissions. The relevant security group tab and specific permissions for this article can be found here: