Tasks can be updated in bulk, at a maximum of 200 at a time (max number of items per page) using the check boxes paired with the “With selected” drop-down menu at the bottom of the task list. A common use of the bulk task update functionality is to close multiple tasks at once.
When the task list is filtered by a single project additional options will be available in the drop-down including changing owners, assignees, followers, modules and milestones. For example:
Note: Bulk moving tasks from one project to a different project is not supported due to source and destination complexities with project permissions and work type/module differences.