My Accounting says the Open Period Mass update isn't retaining the ledger group and Transtype

Details:

1. My Accounting area says when they navigate to setup> business unit related> General ledger> Open Periods mass update and change the Peoplesoft product to a submodule, such as AM or AP, it will remove the ledger group and trans type and grey it out so nothing can be added.
2. I read co-pilot details (with reference to peoplebooks) for this and it says, the only one you can use is GL. (but my accounting area insists they could use AM etc prior to image 53)
3. if it is correct that we cannot change the Peoplesoft product to AM or AP etc on this page, then why is it a look up that INCLUDES AM AP etc?