How to adjust existing additional costs on Sage 300 Purchase Orders

Steps:

Open Purchase Orders > P/O Transactions > Credit/Debit Note Entry.
On the Credit/Debit tab, specify the type of document and the return or invoice for which you are creating the credit note or debit note.
In the detail section, enter the return or invoice quantities, along with cost differences and
quantities.
Click the Additional Cost tab to display the additional cost details.
- Note: If this is a credit note for a return, the program displays additional cost details for the primary vendor only.
Select the additional cost detail that you want to adjust, and then:
1. Click the Amount field.
2. Enter the credit or debit amount for the additional cost.
  - Note: You cannot change the proration methods or accounts.
3. Tab to the end of the detail line to enter a reference and comment.
To change the detail tax class for a selected additional cost:
1. Click the Cost/Tax button or press F9 to open the Detail Costs/Taxes screen.
2. Change the detail tax class, and then click the Calc. Taxes button to recalculate the tax.
To change the total tax amount for the credit note or debit note (including the tax for the
additional cost):
1. Click the Taxes tab.
2. In the Tax Amount column, enter the total tax amount to credit or debit for each tax
  authority.