Doubt about how "import" works

Question

I am learning JS and Reactnative and for that I am studying about the creation of a backend in Node.js and a frontend in React Native and one thing caught my attention.

In my backend when the user is successfully authenticated is sent as a reply a JSON containing the name, email and JWT token.

In my frontend I receive such information and include the token in the AXIOS header to be used in future requests, example:

Auth.js

import axios from 'axios'

export default class Auth extends Component {
   signin = async () => {
        try {
            const res = await axios.post(`${server}/signin`, {
                email: this.state.email,
                password: this.state.password
            })

            AsyncStorage.setItem('userData', JSON.stringify(res.data))
            axios.defaults.headers.common['Authorization'] = `bearer ${res.data.token}`
            this.props.navigation.navigate('Home', res.data)
        } catch (e) {
            showError(e)
        }
    }
}

Well, as you can see I include the token with the command:

axios.defaults.headers.common['Authorization'] = `bearer ${res.data.token}`

So far so good, what struck me is that in other modules I can "enjoy" this token that was added in the header in the module Auth.js. For example:

Tasklist.js

import axios from 'axios'
export default class TaskList extends Component {
deleteTask = async taskId => {
        try {
            await axios.delete(`${server}/tasks/${taskId}`)
            this.loadTasks()
        } catch (e) {
            showError(e)
        }
    }
}

I’m a layman, but it seems that when I import Aces into Tasklist.js, it sees everything I’ve done in Auth.js Moves, including the added token. Is that how import works? Would you have some text on the subject for me to devour?

Until then I imagined import as for example a constant, for example const Xios, so what I did in one module would not reflect in another.

Thank you for your attention