When you enter any Update window, you will be presented with two buttons to decide your final action.

Update buttons when called for Insert new data.

Update buttons when called for Change existing data.

Update buttons when called for Delete the selected data.
Ok/Save/DELETE: The text on this button will change according to which update button you pressed.
If you pressed the "Insert" button, this one will say "Ok", which is go ahead and accept the new data.
If you pressed the "Change" button, this one will say "Save", which is proceed and accept the changes to the data.
If you pressed the "Delete" button, this one will say "DELETE", so you can see the window with its data before actually delete it.
Instead of clicking this button you may also press the Enter key.
Cancel: By pressing this button, you discard any changes or data and exit the window, cancelling the operation.
Instead of clicking this button you may also press the Esc key, or the small X button on the upper right corner of the window.