If you've sent out applications and heard nothing back, the instinct is to send more. That usually doesn't help. It just multiplies the same problem across more employers.
The actual issue is almost always one of three things.
The first is a CV that looks like everyone else's. If your CV opens with a personal statement full of soft-skill descriptions, you've already lost the reader's attention before they've seen anything useful. Cut the personal statement entirely or replace it with two sentences that name something specific: what you're good at, and what kind of role you're looking for. Then get to your experience and education fast.
The second is applying to roles where you're obviously not a fit for the listed requirements. Some job adverts ask for previous experience in the industry or specific certifications. If you don't have those, applying anyway is not always a waste of time, but you need to address the gap directly in your cover note. Pretending it isn't there doesn't work. Acknowledging it and explaining why you're worth considering anyway sometimes does.
The third is no cover note at all. Many teenage applicants skip it because it feels unnecessary or they don't know what to write. A brief, specific paragraph explaining why you want this particular job and what you'd bring to it takes ten minutes to write and puts you ahead of the majority of your competition.
One practical check: ask a teacher or careers advisor to read your CV and give you honest feedback. Not "does this look okay" feedback, which almost always gets a yes. Ask them to read it as if they were a hiring manager and tell you what they'd cut. Most people are too polite to do this without being pushed. Push.
If you've been applying for more than four weeks with no response, change your approach rather than repeating it. The definition of a wasted job hunt is doing the same thing and expecting a different result.