There are two ways to select a country for your session.
User Dashboard V2
1.) Navigate to Services Residential Unmetered page https://app.geonode.com/services/residential-unmetered
2) Under Proxy Configuration, you will see a Country Targeting option

3) Select Country and Port

4) Press add

User Dashboard V1
1) Navigate to IP Gateway page https://dashboard.geonode.com/#/ipgateway
2) Select a Country

3) Select a Port Once you select a the country a list of ports available will be shown.

4) Click Assign to assign the country and port combination

5) Click Save Settings

Via The API
To set a specific country for your session you need to add the parameter country-xx to the username.
Define the county by using two character ISO standards for country codes. A full list of country codes can be found here https://en.wikipedia.org/wiki/List_of_ISO_3166_country_codes
Example: When defining United States as country-us
Replace "username" with your username.
curl -x rotating-residential.geonode.com:10000 -U username-country-us http://example.com