20 May 2014 5:57 am Chandan Singh Parihar Best Answer
I think we can't change the reference field in invoice document.
If you want we change the reference field in accounting document.
For every vendor invoice system generates accounting document.
We can view the accounting document in FB02 / FB03 . Reference field will be stored in header of the document. This field is not editable field. If you want to change to editable field.
Do following settings.
Goto OB32 t.code. click on new entries.
No need to enter account type.
Feild name -- BKPF-XBLNR. activate the field Field can be changed and save.
Now goto FB02. Goto header, now reference field is in editable mode.