In QuickBooks Online mobile app, there isn't yet an option to create a Purchase Order (PO). Alternatively, you'll want to log into your account using the browser and create a PO from there.
Once you're logged in, make sure to enable the purchase orders feature.
Here's how:
Go to Gear icon, then select Account and Settings.
Select Expenses. In the Purchaseorders section, select the Edit icon.
Check the Use purchase orders box.
Select Save, then Done.
Then, you start creating PO's by following these steps:
Go to the + New.
Select Purchase Order.
Enter the necessary information. Click Save and close.
Having the option to create a Purchase Order using the mobile app is a good idea. While we continue to work in making sure we meet our customers needs, please check out our QuickBooks Blog to be updated with our product's latest feature release.
I've included a few helpful resources about using the QuickBooks Online applications: