I am using Aptana Studio 3 in Mac. When I try to set PHP 5.4 environment in project settings, it does not save the changes.
And found this article – http://stackoverflow.com/questions/24633995/aptana-php-version-doesnt-stick-in-project-properties
1. Open project folder
2. Create folder .settings
3. Create file com.aptana.editor.php.prefs and Put below content into created file
4. Close project and re-open