Can someone give me advice on applying for leadership at my job?

I am 21 years old. I was told that getting into management can be hard at my age. Also, we don’t get sent to different stores when we get promoted. You are at the same store.

Usually when I am working registers and no actual leadership is there, I make a list of what needs to get done and I ask who I am working with to pick what they want to do. It usually works out fine.

I am trying to become basically a customer service leader, and I have to know pretty much the whole store. I already know the food side of things, just have to get more comfy on registers.

My store is training me to become a leader.