How can I rearrange the fields/columns showing up in the related tab of a record?
To rearrange the columns/fields showing up in the related Contacts tab of an Organisation you need to mark the required Contact fields as key/header and drag them in the required sequence.
1. Go to Contacts module
2. Click on Customize > Fields and Layout
3. Mark the fields that you wish to see in the related tab view,as Headers/Key.
4. Drag and drop the fields to reorder the sequence
5. Save the layout.