EXPENSE PO WRITE-OFF IN ORACLE 12.1.3

Dear Team,

We have some Expense PO's accrue at receipt to Write-Offs. When we write off PO , system creates reversal entry as below:

Accrual Act - Debit

  PO Charge Act -  Credit

By doing above, negative actual entry is shown in Funds Inquiry which also affected Funds Available balance and since these PO's belongs to previous years, no Budget is there in the current year.

My question is can we credit common Write - Off Expense account, instead of using same PO charge accounts which can vary for each PO. I read about Invoice Price Variance account, but it is not defaulting while doing write-offs. Do we need to modify SLA for this?