Changing Default Accounts impact

Hi Folks,

By mistake we have given Receiving Inspection Account as  Inventory AP Accrual Account. , and created PO's  and receipts in Jul-14 we realised this is wrong, hence we made setup changes.

But my query as follow's.

1. When this setup will work effectively ( I am sure all ready received transactions it will not work), but if we do RTV for those receipts how it will pick the account?

2. Prior to making changes, we have few PO's , which is partially received, will it have any impact?

3. Prior to Making changes we have Partial matched receipts, will it have any impact?

4. Prior to making changes, we have unapproved, Approved but not receiving completed PO's and Receipts, will it have any impact?