Hi @PabbaV71:Can you share some additional details on the issue you are facing.
If this is regarding changing key for a existing data type, please see this.
When you configure source for a data type, you can choose any column as key. Screenshot which you have shown is on pyGuid column. When "Automatically generate a unique ID for records of this type" option is selected in the class rule, pyGuid will be the key for the class and PEGA will automatically generate value for this column when new record is saved.