We noticed that the search field that is showing in the left upper corner of any grid screen has different behavior depending on which table you are.
Released products: it does a wild card search, if you enter any portion of the item number, it will find it
All purchase orders: it only finds the PO when you type in the precise PO number.
For this search box, no parameter exists as we have in the left margin search, like "is exactly" or "contains". it would be better if this search box would behave in every grid as it behaves in the Released products grid. It will see your entry as a ' contains'. This is the most user friendly.