Invoice Approver - change of username

Summary:

An invoice approver has recently changed their Oracle username (which is also their email address as we use SSO) so any historical unpaid invoices are presenting an error when our Finance users are trying to amend the bank account stating that the 'Invoice Approver [approvers username] is not in the list of values'

These historic invoices have already been approved by this user (using previous username) so is there any way to identify how many unpaid invoices there are with this invoice approver (with the previous username) and bulk update them to 'replace' the username to the new one? Otherwise our Finance users will have to manually update the invoice approver every time they come across this error.