[Brian]

Welcome to the forums, Naturalxy!

By default, the Completed button shows you Project view, so it's going to show your actions in their projects, and it's going to sort the projects against each other, while leaving the order of the actions in those projects alone.

No worries, though - you can use OmniFocus' "Perspectives" feature to set up a view that's more like what you're after. (Context view treats actions as individual rows.)

Try the following selections from the menu bar:

View -> Context View
View -> Columns -> Completion Date (if that item isn't already checked)
View -> Sidebar Filter -> All Contexts
View -> Grouping -> Completed
View -> Sorting -> Completed
View -> Availability Filter -> Completed
View -> Status Filter -> Any Status
View -> Estimated Time Filter -> Any Duration

At this point, the window is showing you all your completed actions, grouped and sorted by when they were checked off. If this view does show what you're looking for, you can save it for further use by selecting

Perspectives -> Save window as -> New Perspective.

Now you can bring that view up from the Perspectives menu at any time.

If that view doesn't do what you want, there may be another combination of settings that does. Let us know what you need done differently and we're happy to help.