This is perhaps more complicated than it should be. You can only undo back to the last store, and not to a previous transient version (see the definition of transient in chapter 8). For this and other reasons, it pays to store regularly. To undo back to a previous version, simply browse the history (see section 3.5) and find the version that you want to go back to. Then click on it and on the `Promote' button and store your changes. This view will then be the latest version. You can do similar things on the item level (see section history-item).