How to allow users to change charge account on PO lines when destination type is Inventory

User is trying to create a PO for an Inventory Asset Item. The destination type on PO lines is Inventory. User enters the subinv and its charge account automatically default from the material account mentioned on the Subinv/Orgn setup.
User wants the ability to change this default value to some inventory account but the charge account field on PO line is greyed out, non-editable. Is there a workaround to change the default charge account that is defaulting from subinv/organization? Or fetch the desired charge account from some other setup when the destination type is inventory?