To change the default unit price of an item:
In the left Navigational Column, click Sales tab and then click Invoices.
In the Invoices page, click New Invoices.
Note: You can also change the unit price of items in an existing invoice.
Select the template for the new invoice from the Template Name drop-down menu.
Add item(s) in the invoice.
For more information on adding items in an invoice, refer to Adding Item in an Invoices.
In the added items table under Item, edit the Unit Price entry to change the price of the item.
Click the Save button.
The unit price of the item is updated.