I have been rejected from Macdonalds for crew memebr possition for 7 times what am I doing wrong?

I really need a part time job and unfortunately I am unlucky with finding one although I am desperate and I have applied to Supermarkets, Clothing stores but I am always unsuccessful. I am currently a student and I can't afford anything even MacDonald's rejected me for a crew member position. I am 20 years old and I never had a job before and my mother does not work.