Default regions and subregion can be set at an account level of for each map created.
To set for your account, access your settings here
In the Default Map region selection click on Change.
Make your regional/subregional selection and save.
Now, when creating a new map these setting will be used but can be changed on a map by map basis.
If you don't set these at an account level the first time you select a region for a map you can save these settings.
