Why "he" does not write React.FC on each function?

I learn typescript, and I dont understand why he write in the first Function React.FC and in other function he does not write "React.FC". Why?

exp:

...const Login: React.FC<Props> = ({ signIn }) => { const Add = (id: number) => {   ...  }; return (<div><p>Hello</p></div>)};

Why I dont write React.FC in Add function ?