F-47 field control

Hi Friends

now i met two problem in the T-code F-47.

1) Set the profit center as a mandatory field

2) input the specify value in the field "Reference Key 2"

i have tried the solution below

1)change the FSG for the down payment account

2) use FI validation via OB28

Prerequisite

T-CODE = 'FBA6'

Check:

BSEG-XREF2 ='XXXX'.

But there are not worked in the system.

do yo have any other solution ?