In the main list view of a module there is a little gear-icon that lets you modify what columns are displayed in the list view.
How do I set what columns are displayed in the subpanel version of that module?
You can do that via Studio, accessed via Admin > Studio.
For example, if I want to change the columns for the Contacts subpanel on the Accounts module, I would go to Admin > Studio > Accounts > Subpanels > Contacts.
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