Prevent guests from viewing your profile
When you created your forum account, by default everyone including guests can visit your profile and see your public information. You can modify the privacy settings of your profile, however, to prevent unregistered guests from being able to view your profile, while still allowing registered members to do so.
To set this up, click the Profile button found at the top menu bar, and then click the Edit Profile button found on your profile page. You'll then be taken to the Edit Profile & Statistics page; once here, click on the Privacy tab. When the Privacy page loads, look for the Who Can View My Profile option. If you want to prevent guests from viewing your profile, select the Members Only option. With that set, click the Save Privacy Settings button. Your changes will immediately take effect.