Sophos destination NAT

Hi mates,
I had, few days ago, a particular request : a customer asked me to NAT RDP connection to a custom/specific/non standard port.
This customer has a very good product named Sophos UTM Firewall (version 9.3XX).
I worked with Sophos when it was Astaro....for several years, and my 20-25 customers were fully satisfied.
Anyway......it's easy as you can imagine but I would like to share the steps....maybe tomorrow you have to replicate this and you are too tired to think....you want only to follow (someday could happen)
In particular the customer's IT Dept. decided to change the default RDP port (and also SSH) from 3389 to 33389.