Hi Swathi,
Please firstly follow the KAB 1869472 Abhishekh mentioned below, and implement all the notes in that KBA, and then test with a new PO created from the very beginning.
If you have old POs already affected in production and you don't want to change the customizing in OME9 in production, you could implement note 1915208, then delete the change version of the PO, and do the required changes again.
Regards,
Wendy