How Can I Make My Statement Accept Multiple Results?
I added GROUP BY label_id to make the original statement work.

SELECT `labels`.*, 
       IF((SELECT `label_id` 
           FROM   `customer_print_sessions` 
           WHERE  `customer_id` = (SELECT `customer_id` 
                                   FROM   `customer_accounts_logins` 
                                   WHERE  `id` = '1069') 
                  AND `customer_print_sessions`.`label_id` = `labels`.`id` GROUP BY `label_id`) IS 
          NOT NULL 
       , 'Y', 'N') `in_queue` 
FROM   `labels` 
WHERE  `id` IN (SELECT `label_id` 
                FROM   `customer_groups_label_relation` 
                WHERE  `group_id` IN (SELECT `group_id` 
                                      FROM   `customer_accounts_group_relation` 
                                      WHERE  `customer_id` = 
                                             (SELECT 
                                             `customer_id` 
                                                              FROM 
                                             `customer_accounts_logins` 
                                                              WHERE  `id` = 
                                             '1069' 
                                             ))) 
ORDER  BY `labels`.`plu` ASC;