It would make sense that the Admin can view all orders.
Are you sure the note below (from the orders api page) not the result you're seeing?
As of June 6th, 2018, only the last 60 days' worth of orders from a store will be accessible from the Order resource by default. If you want to access older orders, then you need to request access to all orders. If your app is granted access, then you can add the read_all_orders scope to your app along with read_orders or write_orders.
★ I jump on these forums in my free time to help and share some insights. Not looking to be hired, and not looking for work. http://freakdesign.com.au ★