Cannot Edit Fields to Display in Queue List View in Lightning Experience

To resolve the grayed-out "Fields to Display" option in a Queue list view, first verify the user has the required permissions to edit list views, then confirm the user is a member of the queue.

Option 1: Check List View Edit Permissions

If the issue is related to permissions, contact your System Administrator for assistance. The user needs the appropriate permission to customize list views on the object in question.

Option 2: Verify Queue Membership

Only queue members can edit a Queue list view in Lightning Experience. This is because system-generated list views for queues are restricted to queue members.
To add the user to the queue:

1. Navigate to Setup.
2. In the Quick Find box, type Queues and select it.
3. Click Edit next to the relevant queue.
4. Add the user under the Queue Members section.
5. Click Save.

Salesforce Classic Workaround

In Salesforce Classic, if a user has the required permission to edit list views on a given object, the user may edit a Queue list view even if they are not a queue member. If the user is not a queue member but has the required permission, they can switch to Salesforce Classic as a workaround.