Select the "Modify Title" icon.
On the "Modify Title: Item Lookup" screen, enter Item id using the system generated barcode for the reserve you wish to modify.
A screen with four tabs will appear:
Control: Generally will not need to be modified unless the record format is anything but temporary. And the date cataloged is anything but never.
Bibliographic: Will allow you to make changes to the 100, 245, and the 856 fields.
Call Number/Item: This screen allows you to change call number and item Barcode.
Bound-with: Disregard. There should be nothing to modify within this tab.