How to Change vBulletin Forums as Home Page Replacing What’s New Activity Stream

Beginning from vBulletin 4.2.0, the default landing page (vB calls it as tab) when a visitor visits the homepage of the community forums for new installation or existing vBulletin-based site that was upgraded to latest version is set the the Activity Stream page under the “What’s New” tab, which served via the activity.php script.