Change Withholding amount in Modify Invoices

An invoice was posted that included Vendor Withholding. In Modify Invoices, where do you change this Withholding Amount?

• Munis 
• Accounts Payable 

New functionality to user

• While on the Invoice in Modify Invoices, click on the Withholding Folder, which should be lit up Yellow
• On this screen, there is no Update option, but there is a hyperlink button marked Modify 
• Click Modify, and change the Withholding percentage or amount
• Click Accept to save the change

If the Modify option is not functioning, make sure the user has Accounts Payable role permissions to override retainage amounts