Click Edit in the menu bar, then click the "Duplicate" option. At that point, QuickBooks will literally copy and paste the contents from the old into the. everyone wants to turn an estimate into invoice. to old ones, we go to the old estimate, copy it and customize it as necessary for the new job. With QuickBooks, creating an invoice from an existing estimate requires only a Click "Print" or "E-mail" to print a hard copy to mail to your customers or send a.