It's not completely straight forward, but a Task Due Date is typically a Planned Completion Date. That's the date that drives your predecessors and your critical path etc. and is controlled by the PM. The date you have pictured is the Commit Date, which is controlled solely by the Assigned person(s). The PM can't change this. This is the assigned person's way of telling you (the PM) when they'll be able to complete this (you'll get an email when they change it). Then you as a PM have to either accept it and change the Planned Completion Date to match, or have a conversation to negotiate a date. The Commit Date will initially be set to your Planned Completion Date (usually – sometimes it's weird). So they should be the same initially. But once the person changes the date, it stays that date until they change it again. For me, I create a view to show both dates so I can ensure they match. If they don't, I have to somehow make them match (have a conversation or just match them). See attachment (never mind the dates they're from my playpen project �� ). So for ease, think of it this way: Due Date = Planned Completion Date = PM's Date Commit Date = Assignee's Date Hope that helps.
