In this PMWorld 360 video, Alison Mills-Long discusses how to document project changes. She details some of the basic information that should be included in the documentation. Documentation of project changes should also include information on what changes need to be made, why they need to be made, as well as the impact of those changes such as benefits or areas that will be affected. Alison also indicates that the documentation should indicate any changes to the schedule or expected delivery time as well as the budget.
For more information check out How to develop an effective change management plan.