In this transaction you are able to assign scenarios and customer fields to ledgers which we should already have.
IMG Path: Financial Accounting (New) -> Financial Accounting Global Settings (New) -> Ledgers -> Ledger -> Assign Scenarios and Customer Fields to Ledgers
Tables: T881, T881T, FAGL_LEDGER_SCEN, FAGL_SCENARIO, FAGL_SCENARIOT, FAGL_CUST_FIELDS, T894, T894T
When you open the transaction you will see the list of all available ledgers. Highlight one of them and check their related Scenarios, Customer Fields if such exists and Versions.
Scenarios for Leading Ledger in this example.
Customer Fields screen.