One of the great features in Premiere Elements is the History panel. This is where a complete history of your project is kept. As you add media, drop items on the Timeline, add effects, add transitions, and make edits, the History panel keeps track of all these activities. You can revert back to any point in time just by clicking on that point in the History panel. As you work through your project, keep an eye on the History panel to see that everything you do is recorded there. Whereas the Undo and Redo buttons on the taskbar take you forward or backward through the project history one step at a time, the History panel allows you to jump backward and forward in leaps. By clicking a history item early in the project, you can revert back to what everything looked like at that point; then you can jump forward in time again. You also have the ability to delete a history item and clear the history by right-clicking the History panel or by clicking the More button in the panel's title bar.
The History panel.