some completed tasks stay visible
in some of my projects the completed tasks are "hidden" in other projects they remain visible in the list. I have not yet figured out the "pattern" behind this behavior and basically just want all of the completed tasks to "gone" unless I specifically select to show completed tasks.
Are the completed tasks 'Child' (sub) tasks of 'Parent' tasks? (are the tasks indented?) If so, that behaviour is by design; these type of completed tasks will stay checked off, but visible, until the Parent Task is complete. If you'd like to immediately have the Child (sub) Task move to History When you complete the task, hold down the [Shift] key when you complete the task.
I figured that completed sub tasks stay until the parent task is completed, but in one case I have ten completed tasks still in the list that are not a sub task.
Maybe those were sub tasks earlier on? I just "shift'click" completed them and now they are gone. Thanks for that tip.