Undoing and redoing operations
As you make changes to your drawing you can undo them to return to an earlier stage. You can also redo changes which you have undone.
To undo and redo operations
1. Select the document where you want to undo or redo operations.
2. From the Edit menu, choose Undo or Redo.
Tip
However far you go back through undo steps, as soon as you edit the document yourself you will no longer be able to redo any of those steps.