Hey, confidence is a broad topic made up of a lot of skills, habits and forces. Think of it as an ecosystem of parts... To speak simply, it comes and goes. Like waves. No one is 100% confident all the time. You're 'secure' around people you hang out with because you're comfortable around them the same with the area you focus on. That's not confidence. Confidence is elusive and reacts well with the unknown. You cannot play safe with confidence. You have to go outside the barriers and push limits further than you can imagine. No one can guarantee confidence, but you, its a road of bumps and bruises. Hit the gym, work on your appearance, take daily risks and expand your knowledge, you'll feel better about yourself to harness the power and responsibility that comes with confidence. Which most don't. Most people fake it to make it. This doesn't work. It's like building a robust program. Strong code, strong functionality, Great User Interface. You got a hit. Fight for something in your life. That's a huge one, that's where passion lives.
Check out a book called Think and Grow Rich by Napoleon Those are the 13 skills to master to become confident. Real World Experience that you can use immediately. Books on Leadership is another great resource.