Dear Ajay Nagargoje,
System refer PO for Migo not info-record.
And PO refer's values of info-records at the time of PO creation, in between if you changed info record, PO values will not get changed.
Changing Open PO's values isnot recomdable. If you need New Value PO you need to go for New PO's.
Refer this link,
PO price changes after partial MIGO
Reg,
Bhg.
