Once you have sent a document out and assigned a deal value to it, you may want to update the amount it's worth. In our web app on the desktop, you can do that from either the deal board if it's a sales document or in the document summary.
How to update deal value from the document action menu
Go to the active document
Click in the field that says "Value (currency)"
Enter the new deal value
The deal value is only visible to the sender. It won't affect the document in any way and is mainly used for internal statistics.