Do a search on this in this forum. There are comments on a previous thread about this.

repeating what was previously posted and anything else we have learned in the meantime....
 
DBA Classic would save the voucher description as the GL Transaction description - you had no choice and it all happened behind the scenes
 
Users requested and IS Tech update added the ability to edit the description line by line.
 
On the first release, Users complained that with the requested update, if they didn't want to enter a line by line description, the GL Account description was what was saved for each  line.
 
We changed AP-B to do the foillowing - when the GL account is entered, the account description is displayed to confirm it is the right account.  If no changes are made, when you advance to the amount field, you will see the header pull down to the line item description which is what will be saved to the GL transaction.   If you have made any changes to the line item description, they will be saved.
 
Some users are still seeing the GL Account description being saved - we are working on what causes this.