EAC hours are pushing dates around. Move dates, EAC goes back to an incorrect number.

Two things with regards to the issue you’re having. One, you want to have the activity planned & scheduled before marking it as started. Two, the different types of activity types will determine how the each piece will change as you change the conditions of the activity. You can find information on duration types in Primavera here Duration Types. You can also find it in Lesson 15 of the user’s manual. The chart below is also a great point of reference for helping you determine the activity type you desire.

Activity Duration Types	When you change units, what changes?	When you change duration, what changes?	When you change units/time, what changes?	When you add a resource assignment, what changes?
Fixed Units/Time	Duration	Units	Duration	Duration
Fixed Duration & Units/Time	Units/Time	Units	Units	Units
Fixed Units	Duration	Units/Time	Duration	Duration
Fixed Duration & Units	Units/Time	Units/Time	Units	Units/Time