When you complete a change request, the Apply Schedule Changes and Apply Cost Changes step actions apply the changes to the live project. In order to preserve edits that occurred during the approval process, the system only replaces the information that was changed in the change request; not the entire activity or work package.
For example, if you change activity duration then only duration is changed when the change is applied to the live project. And if you make a change to a resource assignment, then only that resource assignment is changed in the live project. You can view the information that has changed in the Summary view.
The one exception to this is when the change class is a forecast class and you manually change a forecast date on a work package that has not yet begun. In this case, both the forecast start and finish dates are copied to the live project along with the time phased forecast. Including both the start and finish dates ensures that a date error, such as the start date being after the finish date, doesn't occur when you have multiple changes occurring on the same work package at the same time.
When a Forecast Change request is completed, the EAC and EAC Hours stored on the work package are updated to include the change amount. If you use the forecast preference Scale EAC, the values in this field are used to adjust the EAC by the amount in this field. If you use this forecast method, ensure that actual costs have been posted and the forecast calculated before completing the change request. This will make sure that running update totals on the EAC field will reflect the amount in the change request.
See the Forecast Change request form field descriptions