GL95.1 Major Account

Hi all!

I'm needing to restrict the values that are available for selection on the GL95.1 screen under the Major Account.  I was to restrict it so that only one account is available for selection.

Apparently the fields are FR-ACCOUNT and TH-ACCOUNT.
Neither of them seem to be defined as an element.

Any ideas on how to restrict the field?
Even the ability to only allow that value to be inquired upon would work.

Thanks