Before you can select the settings Accept Non Checked and Balances Invoices Only or Accept Checked and Balances Invoices Only the setting Accept and Alter Invoices must ticked first.
These settings are found here:
Click into the Admin Cogs
icon along the top bar.Click into Organisation Administration on the left.
Click into Roles and Edit the role that needs updating.
Click into the Permissions tab and into the Order Management section.
Tick Accept and Alter Invoices.
Click Update.