Break link between Remaining duration and percent complete

% Complete is based on duration. Therefore, any adjustments to remaining duration will adjust the %Complete. This is logical as %Complete = Current Duration/(Current Duration + Remaining Duration)*100. Current Duration = Overall Duration x %Complete. The easiest way round this is to define tasks as fixed work. Then update the %Work Complete when updating tasks. It is then possible to update the remaining duration without impacting the %Work Complete. In this situation, when updating the schedule, the remaining work is spread across the remaining duration. Hope that helps?