I'd be pleased to help share information about the automatic numbering of Purchase Orders in QuickBooks Desktop (QBDT).
A purchase order keeps you on top of your inventory as it helps track the items ordered and received. Knowing what expenses to expect helps you manage your funds wisely. In addition, purchase orders have the automatic numbering in QBDT, as of now, we don't have the option to turn off or stop this feature.
If you wish to change the number entered by QuickBooks, you can remove the number under P.O. No. and enter the desired number you want.