How to change default order status to Processing

I have this plugin installed and enabled for a school/student microsite, but I do NOT want to the order status to change to “completed” immediately when payment is processed because it still needs to go through fulfillment. How can I set it up so the payment status = “Processing” when payment is approved through Moneris? Then the team will manually update the status through to Completed after the order is fulfilled, shipped. etc.

We’re using the paid Moneris plugin (from Skyverge) on our main site annexpro.com, and do not have this issue – the order status goes to “Processing” once submitted.

The page I need help with: [log in to see the link]