You are using phpFox version earlier than 4.6.0? Please refer instruction for this article here.

You may want to set the Redirect after a user joins or logs into your site. For example, new users tend to have a hard time finding the privacy settings and don't always see the tutorials you might have made. You can set a redirect after signup to the privacy page. We'll use that as our example for this tutorial.

Redirect After Signup

Please note to clear cache any time you make any changes.