Source: Dynamics GP Documentation
With the October 2020 release of Dynamics GP, you now have the ability to bulk-edit the columns on a SmartList.
In order to see this new functionality you will need to start by opening SmartList (choose Microsoft Dynamics GP, and then choose SmartList). You’ll then navigate to the specific SmartList that you want to edit, such as the default Sales, then choose Customers, and then choose the Columns button: