Change the status of the order on its page: choose the status and press "Update status". The back office adds a line to the history of the order.
Examples
When I change the order status to "Payment accepted"
When I change the order status to "Canceled"
When we change the order status to "Shipped"
And I change the order status to "Processing in progress"
When I change the order status to "Awaiting check payment"
Pattern
When(/^(I |we )*change the order status to "([^"]*)"$/, …)
Part of @webship-js/prestashop-steps (github.com/webship/prestashop-steps), a step pack for Webship-js 2.0.x.