A task is created for a project, version, feature or folder. After the task is created you can move the task to a different version, feature or folder. So for example the task might be created against the project where it appears in the backlog. A manager can move this task to the version in which the work for the task should be implemented.
To move one or more tasks select them in the list, right-click and select 'Move'. This will launch the Select Stream dialog.
Select the project, version, feature or folder to move them too and press 'OK'.