Unless a user is assigned to any of the sample locales, they would have defaulted to using the default locale specified in the Global Settings.
AyaNova now installs with four sample locales English, Deutsch (German), Español (Spanish) and Français (French)
The default locale is set to English in Global Settings. Refer to the Administration section in the AyaNova v3 manual for details on setting Global Settings.
To change the locale for an existing user - select the drop down for the Default Language field.
Remember, a change in locale does not take effect until the user exits completed and next logs in. This is because localized text is loaded when the user first logs in only.