Click the 
button on the ribbon quick access toolbar.
Press CTRL+Z.
To undo the last operation of data change:
Click the button on the ribbon quick access toolbar.
Press CTRL+Z.
If changed data was saved and then the saving operation was undone, previous values will be returned. Those values will be highlighted as changed and to further use them, save them.
To redo the last undone operation:
Click the 
button on the ribbon quick access toolbar.
Press CTRL+Y.
The / buttons on the quick access toolbar are active on changing data.
On refreshing data entry form and calculating algorithms for saving, the operation history is cleared and the / buttons on the quick access toolbar are disabled.
When working in the web application, use undo/redo operations to:
Change data.
Format cells.
See also:
Working with Ready Data Entry Form