Hi Gina
First thing is for you to create a test company to try this on. Lets be safe to make sure it works.
I am assuming that if you look at your company account format:
Microsoft Dynamics GP > Tools > Setup > Company > Account Format
It will be setup showing in the Account Length field 66 Characters and 10 segments in the Segments field which is the same as the Maximum Account length and the Maximum segments.
You have the following segments setup
Segment 1 company 2 characters
Segment 2 Department 3 characters
Segment 3 main account 4 characters
Segment 4 Product 3 characters
Also in the list would be
Segments 5 through 10 all with 6 characters.
If the above is not correct let me know.
Now assuming that you have no GL account numbers in segments 5 through 10 and the GL account numbers use only the first 4 segments, this is what I want you to do. Again this is in your test company first. Ideally you will have no batches in GL while you do this.
Change the Account Length to 12 (2+3+4+3 which is the actual size of your GL account) and the segments to 4.
Click on OK to close the window
Next run reconcile on your GL accounts starting with the first historical year and moving forward until you finish the open year. ( Microsoft Dynamics GP > Tools > Utilities > Financial > Reconcile)
Next Run a Reconcile on the Account format setup
Microsoft Dynamics GP > Tools > Utilities > System > Reconcile
Select Account Format Setup
Validate your data.
If all looks good then you can do the same steps in your production company. Make sure you have a very good restorable backup of your production company before starting.
Once you have finished the production company reformatting, you should most likely rebuild your Management Reporter Datamart to give it a fresh start.