It’s pretty obvious you will want to customize your packing slips and invoices you use in Magento with your company logo and address information. We’ve seen some posts in the various forums that suggest modifying core code files in Magento. DON’T! It’s actually very simple to customize your packings slips and invoices in Magento.
First, log in to your Magento admin. Go in the top menu to “System>Configuration”. Make sure you have selected your store view near the upper left corner under “Current Configuration Scope”.
Look in the left column and go to “Sales>Sales”. You’ll see a selection on that page for “Invoice and Packing Slip Design“.
Enter your info and there you are, customized packing slips and invoices in Magento.