I'd like to help you out with your concern, slz1.
To clarify, are you logged in to QuickBooks Online using the browser? If you are, you can find the Gear > Account and settings in the upper right-hand corner of the page.
Here's a sample screenshot for a visual guide:

To send purchase orders, you can select Save and send from the drop-down menu next to Save. I've a sample screenshot for reference:
For printing the packing slips, you can read the articles below: Create and print a packing slip.
If you're using QuickBooks Desktop, you can un-apply a credit from an invoice by following the instructions in this article: Remove or unapply a credit from an invoice or bill.
Please let me know in the comments below, if you're referring to something else. I'll get back to you as soon as I can.