Manage Your Posts Only

makes it so that users and editors can only see posts from the manage tab that they have written themselves. By using this plugin, the only users that can see all posts from the manage tab are Admins.

function mypo_parse_query_useronly( $wp_query ) {
    if ( strpos( $_SERVER[ 'REQUEST_URI' ], '/wp-admin/edit.php' ) !== false ) {
        if ( !current_user_can( 'level_10' ) ) {
            global $current_user;
            $wp_query->set( 'author', $current_user->id );
        }
    }
}

add_filter('parse_query', 'mypo_parse_query_useronly' );