Bulk profile update for JIRA users from Groovy script on script-runner plugin.

changeUserTimeZone.groovy

/**
* This script was succesfuly tested on JIRA 6.1
*/

// import JIRA Component Accessor
import com.atlassian.jira.component.ComponentAccessor
// Create a new instance
cA = new ComponentAccessor();
// Get all application users
users = cA.getUserManager().getAllApplicationUsers();
// Loop on every user
for(user in users){
  // Get the UserPreferencesManager
  cA.getUserPreferencesManager()
    // Get user ExtendedPreferences
    .getExtendedPreferences(user)
    // Set notify own changes to true
    .setString('jira.user.timezone', 'America/Los_Angeles');
}