You can create line item adjustments that either increase or decrease the line item total. Normally, this is used to provide a discount so the adjustment will be a negative percentage or amount. When the line total is posted to the GL transaction, the amount after adjustment is posted to the GL as revenue.
You can also choose to post the amount before adjustment and the adjustment itself into the GL transaction. Activate the setting Setup, Feature Settings, Invoices, Book Line Total as Revenue Before Adjustments.
You would also need to go to Setup, Company, Adjustments and specify which GL account to use to post the adjustment amounts. Edit any of the adjustments you have and choose the right account under GL account. This account is typically an expense or contra-revenue account for negative adjustments ( discounts on lines), revenue or contra-expense accounts for positive adjustments(surcharges on lines)
Versa will first post the line total before adjustment as revenue and then post the adjustment as an expense (if you choose to use an expense account for the adjustment). This means any discounted lines will have item before discount recognized as revenue, the discount itself is recognized as expense. If any adjustment with no associated GL account is used, the system will behave as before and only post the total after the adjustment to the GL.
If you prefer the adjustment to have no effect on revenue, you can choose to use a contra-revenue account when setting up the adjustment type. The adjustment will reduce the revenue instead of booked as an expense.