The last tab is labeled Updates.

This is where updates to the (published) Daily plan are to be created.

Consecutive updates are listed sequentially, allowing you to either delete (with the Delete button) or modify them (with the Edit Daily Plan Item button):

Adding an update

Click on the Add button to create an update entry. Doing so opens a new instance of the whole editing content of the Daily Plan, allowing to make changes to any of its parameters. This allows to keep track of modifications - and tells the NOP to use the last saved (and published) version of the Plan.

Do not forget to click on the Apply or OK button to store your changes in the current View.