1. On the server hosting the Web UI and RESTful API websites run the IIS Manager by accessing Administrative tools > Internet Information Services (IIS) Manager.
Other ways of accessing IIS Manager are shown here
2. Select a website that requires port change:
3. In the pane on the right in the Edit Site
section click Bindings
4. In the pop up window, select a binding and click Edit
5. Set the new port and Save