Updating PO Variance account

Content

Hi team 

We have updated the transaction accounting definition for PO Variance account to default to PO Charge account irrespective of any conditions . However , when trying to update an existing Purchase order by raising a change order and then changing the PO charge account , its still defaulting from the requisition line associated previously . 

Additionally , on trying to edit distribution , the Rebuild Account option is not showing up  

Did any one else face such issue

Thanks

Rohan