Need more information to say whether or not your overview as admin should show more. Overviews should show what they are setup to show. Even as an admin, you can configure it so that you only see certain tickets.
I’m assuming you created an overview called ‘Open Tickets’ and made that overview available to ‘Agent’ with no restrictions to users.
For your users only seeing 3 of the 6 tickets. Assuming the first image is the overview in the last image, I would start looking at other factors that can limit what a user can see like Roles and Groups.
Even though your overview shows 6 tickets in the one, there could be something else that is limiting it to 3 for that user.