In order to change out of the box page messages within Liferay, one must configure the properties of the language.properties located in the portal-impl.jar/content/language.properties
Resolution
The master language.properties file is used in Liferay to display portal content. This also allows portlets and other content to be localized. This file is stored in the default portal-impl.jar in the "../content" directory.
To properly override the default language.properties file, a "content" folder should be created in the following directory of the application server:
../ROOT/WEB-INF/classes
This should be the same location where the portal-ext.properties is stored.
Using the English localization, the following are filenames that should pick up the overrides:
Language-ext_en_US.properties
Language_en_US.properties
Language-ext_en.properties
Language_en.properties
Language-ext.properties