PHP Code:
// ****** USERS WITH ADMIN LOG VIEWING PERMISSIONS ******
// The users specified here will be allowed to view the admin log in the control panel.
// Users must be specified by *ID number* here. To obtain a user's ID number,
// view their profile via the control panel. If this is a new installation, leave
// the first user created will have a user ID of 1. Seperate each userid with a comma.
$config['SpecialUsers']['canviewadminlog'] = '1';
There you can set who can view the logs.
PS You only to need to read the descriptions in the config.php file to know what the purpose of these settings are.
More info also in the manual:
Editing the vBulletin Configuration File