Define earned value settings for a specific work breakdown structure element

Choose Project, WBS.
Select the WBS element whose earned value settings you want to define, then click the Earned Value tab.
In the Technique for Computing Performance Percent Complete area, choose the completion percentage method you want to use when calculating an activity's earned value.
In the Technique for Computing ETC (Estimate-to-Complete) area, choose the method you want to use when calculating an activity's Estimate to Complete (ETC) value.