Hi Tanya,
Open an invoice, at the top there is a print button with dropdown. Click the dropdown and you will find a packing slip.
In the templates list you will find the delivery note template - you can modify this if you wish. If you do modify and create a new template......you then need to go to the Edit/preferences/sales & customers/company preferences and select the template you wish to be the default template for packing slip that you want to use for printing.
Gillian