how to enable a ff desc field for an accounted journal

Hi there

We are using a descriptive flexfield for grouping porpuoses at journal line level, but journal entry form becomes not updatable once its posted

In some cases, we need to update this value ( in desc flexfield), but field is greyed, even if journal was posted ( accounting process run every 5 minutes)

Is there a way to make this field updatable?

tks in advance :)

lilian garcia