I am running a project and some tasks are delayed, so I need to update the gantt now with later end dates for these tasks and coreesponding later start dates for depended tasks. However, I dont want to loose the original dates before this delay, I want to be able to see how much each task was delayed from the initial plan, how can I do this?
You can do it with BaseLines:
The baseline is a snapshot of the project state at the moment when you create de baseline.
If you change the project after that snapshot, you can see in red the delayed tasks and in green those that are finished earlier.