How do you alter which fields are displayed in the related section for a custom module on the app

How do you alter which fields are displayed in the related section for a custom module on the app

As the subject really. We use a lot of custom modules. However when the records are shown in the related list on the mobile app, I can't see where you select which fields are displayed? currently it's the key field and the owners name. I need to be able to change these fields. We use a lot of model numbers for things, but where they don't exist the field shows "Unknown" however loads of our records are like this so you end up with a big list of records that all state "Unknown" (they are slowly having the correct model set) however we could see what the record is if we could view the registration number field or one of our other fields. Owner does not need to be shown as it's not a field with any value in this particular module.

Surely there is a way to set what fields are displayed on the app? if not when is this basic functionality coming?