Navigate to GENERAL > Settings > General > Workflow in the left menu of the back office and select the Order status tab.
Click the green plus icon in the navigation at the top of the screen to create a custom status.
A pop-up window will open, where you can enter the desired status in the Title field.
Click Send at the right at the bottom of the window.
Adding a custom status to orders
Navigate to SALES > Orders in the left menu and select the order you want to add a custom status to.
You will be taken to the order dashboard. You can set the order status at the right at the top of the screen. Select the desired status in the Status drop-down menu. This section will only be visible when you already have created (an) order status(es).
Click Save & continue at the right at the bottom of the screen.