EAP 9.2 Update Open Item

Can someone please explain how the Update Open Item component works (Accounts Payable > Vouchers > Add/Update > Update Open Item)?  We are trying to use it to change the Open Item Key on a voucher from one value to another.

We created a voucher using an account requiring an Open Item Key.  We entered the wrong value (on purpose, as part of testing).  We posted the voucher and ran Journal Gen.  We then navigated to the Update Open Item component.  We entered the BU and the key that was entered (the wrong key).  When the component came up, if we go to the Details section, can we change the Reference to be the correct key?  If so, how do we get that over to the GL?