How to update the DFF on a posted Journal line? System is not allowing.

Summary:

Manual Journals have been posted in the system and the period is closed.

The user wants to update the Journal lines descriptive flexfield values for such journals but not able to edit/update the journal line.

Content (required):

The journal DFF flexfield is context sensitive:

Context: AMI PO Accrual

Attribute1: Vendor Name

Attribute2: PO Number

Please help. The DFFs are not even visible on the GL Journal Line after it has been posted.

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):