Menu:
Editing Data
Typing the data in the cell again
1. As described in entering data, you can change what has been entered into a cell by highlighting the cell with your mouse, or moving to the cell with the arrow keys and re typing the data.
Edit within the cell
1. Rather than typing out all the data again into a cell, you can edit the
cell.
2. Move the mouse cursor to the cell you wish to edit.
3. Double click on the cell.
4. Edit the data in the cell, then press enter.
OR
1. Move to the cell you wish to edit.
2. Press F2 (Function key 2, found on the top left of the key board).
3. Edit the data in the cell, then press enter.
Undo and Redo
1. If you have made an error in retyping data, or wish to go back to the
previous data, you can press the undo icon, found on the tool bar.
2. If you want to go forward to what you had edited, you can press the redo icon.
Undo 
Redo