Form Personalization for Move Order Form

On move orders form i am having header and lines section the header section will contains some DFF's as follows

The user will enter all the details and save the record. Now if User A has loged in he has created the Move order and CPP Approver is B. So now the user A cannot approve the move order.

When the user B logins only he can Approve the move order. I want to achieve this using form personalization.

I have tried all the ways..i have tried this for all the trigger events.

e.g

Trigger Event: WHEN-NEW-ITEM-INSTANCE 

Trigger Object: TOMAI_MAIN_HEADER_BLK.DONE