Summary: 

If you want customers or product groups to appear in the transaction tab of your product records it will need to be done in your Transaction Enquiry Report first. The default grid layout set in your Transaction Enquiry Report will then flow on to the Transaction Tab in your Product Record. 

Steps:

1. Navigate to Reports
2. Click Inventory
3. Click Transaction Enquiry 
4. Click the Show Toolbar tab
5. Click on Hidden Columns
6. In the dropdown, find the intended field (customer, product group and etc) 
7. Drag and drop the field in to the Transaction table.
8. Save it as a Default Grid Layout
9. Refer back to the intended product record
10. Review Transaction Tab with new layout in your Product Record.