When setting up a new project and a new task, it appears that the only default setting is to have a Backlog column of open tasks. Resolved tasks simply disappear then.
While it is really good that workboard lists are customizable, the default workboard should have columns that:
# Work: meaning the user should be able to use them without customizing the columns unless they want to
# Give the user hints about how a workboard functions, compared to the generic open tasks lists you see in the default project view. Having a few default columns should make it obvious to the user that they drag tasks between the columns, etc.
To accomplish these goals, I'd suggest adding two additional columns to the default workboard view. First, something like "Doing" or "In Progress", and then a column for "Resolved" or "Done".