Property of the ScriptLine: International.
The Muslim Data Source property editor contains 2 tabs.
The Prayer Times tab contains the settings used to specify which Muslim Times Source(s) should be used to evaluate Muslim time tokens. There can be many times sources selected in the same diary, as prayer times depend on one's latitude and longitude (in analogy to sunrise and sunset) and therefore most diaries that contain Muslim prayer times will display them for many cities across the country.
In the International Preferences, you can specify a default Muslim Calendar and Muslim Times Source(s) to use by default for any new Script.