We have just started using Jira and now that we have completed a few sprints we realise that we want to add a "Fix Version" to all our tasks so that we can start getting a meaningful version report. I know how to "bulk change" items in the backlog, but I haven't found a way to multi-select completed items so that I can "bulk change" the completed items to include them in the history of the "Fix Version". Is there a way to do this?