Is anyone a hiring manager?

I want to know because I want to know what I'm saying that makes these people think "No, she's not right for the job." It's not like I'm interviewing to be a stockbroker.. or something that requires serious skill and a degree. I'm applying to be a sales associate, cashier or server at clothing stores and restaurants! Which will literally hire anyone, but supposedly not me. I go in these interviews with confidence, say all the right things, go home thinking I got the job, wait a few days, follow up with a call, and always get told I wasn't considered. I've been searching for a year now. I just graduated in June and I'm just trying to save up a little money for college next year. Any hiring managers out there I can talk to who will help?
My email is: catsi8101@gmail.com