[Cryo]

You have to do two things. First, login to your Admin CP and go to vBulletin Options -> vBulletin Options -> User Registration Options, scroll down to Message Editor Interface and switch it to Show Enhanced (WYSIWYG) Editor Toolbar. Save - this will set it as the default for new users.

Next, to change the setting for existing users, go to Maintenance -> Execute SQL Query. Under Automatic Query scroll to the bottom and select Show Enhanced (WYSIWYG) Editor Toolbar. Click continue, and you're done.

If it tells you that you don't have access to execute SQL queries you need to open up your ./path/to/forums/includes/config.php file and change the setting for "$config['SpecialUsers']['canrunqueries'] = '';" to include your user id. For example, if your user id is 1 you would change the line to read...

$config['SpecialUsers']['canrunqueries'] = '1';

Hope that helps!