How do I see the list of all versions of a particular Purchase Order (PO)?

You can find all versions of the PO as below:

1. Click on Orders > Purchase Orders / Orders and Releases.
2. Under the Edit filter section, enter the PO number in the Order number field.
3. Select the Exact match ratio button below the purchase order number.
4. Click Apply.
5. All versions of the PO will be listed below.

If you are unable to see the Orders tab, please see Why can't I see the Orders and Invoices tabs in my SAP Business Network account?

SAP Business Network for Procurement & Supply Chain
SAP Business Network for Procurement & Supply Chain > SAP Ariba Supply Chain Collaboration > Supply Chain Collaboration - Order Collaboration
SAP Business Network for Procurement & Supply Chain > Transaction Documents > Transaction (Purchase Orders, Ship Notices & Goods Receipts)