Please help provide solution of how to adjust/rearrange list of Urgency in Incident Form

Please help provide solution of how to adjust/rearrange list of Urgency in Incident Form

We have question from customer regarding how to adjust list of Urgency in Incident Form.

In Incident Form, there are Impact and Urgency which you have to select Impact first before select an Urgency. 

However, an Urgency list in default it arrange by ascending like from a, b, c, d, ... z. If you see from picture it start from High, Low, Medium and Urgent. From that point, we would like to know if we can rearrange or adjust it at the backend by ourselves. Example of when we click drop down from Urgency it will show as Low, Urgent, Medium, High.

Is it possible to do that? If yes, please help provide solution or steps of how to do it. But if not, can you help suggest the best way of how can we manage it.

Thank you.