How do I give a Discount after the Invoice was Posted?
If you edit an Order from the Invoice and change the lens or frame, the discount will need to be added manually. The Global Discount button is not available after the invoice is posted.
Here are the steps to add discounts by line item. Also there is a short video you can watch on this workflow.
This video does NOT have sound. Click the full screen icon in the lower right of the video if you want to view a this in a larger screen.