Use the Undo and Redo buttons to step back to correct any mistakes. The Undo and Redo buttons will work for all edits to the model(s) within a single session.
Use CTRL+ Z to Undo and CTRL + Y to Redo an action.
If you accidentally Undo loading the model, use CTRL + Y to re-load it without the loading time.
All model actions are recorded in a single sequence, Undo/Redo operations are not stored on a per-model basis.