The order statuses on the orders page should mirror your order statuses in your Ecommerce backend (such as Webflow, Foxy, Duda, etc.). So if you change a status in Monto or your Ecom backend it should be reflected in the other.
Unfulfilled
This is the default automatic status that is used for all orders until you update it
Fulfilled
This is a manual status that is typically used when a shop has shipped an order to the customer.
Marking an item as shipped or fulfilled in your ecommerce platform will change your Monto order to "Fulfilled"
Refunded
This is an automatic status that will be applied to an order which has been either partially or fully refunded to the customer