Question
When Producing a Parts Invoice and The Issue Price and Discount Field are Greyed Out. How Can This Be Amended?
Answer
Upon entering the following screen:
Parts > Sales > Invoice
After selecting a customer, and part within the below example the Discount % and Issue Price can be amended, meaning that the user would be able to change this. However, for users who have this greyed out then they would be unable to this. 
This is due to the access level, and can be amended within:
Parts > Parameters > Department Details > Parts Maintenance
Within this screen, select amend. Here Price Amendment and Part Amendment can be adjusted in order to allow the user to amend the Discount % and Issue Price.