Changing language programmatically

[hroma]

I'm trying to add a language switcher inside an existing navigation bar.
Everything works as expected except changing the locale.

When I click on the link, the emitted value I retrive is the lang (i.e 'en').
Now, how do I programmatically change the locale inside a function like this:

const navClick = (event, item) => {
    alert(item.lang); // ok it return the locale 'en' clicked
    useI18n().locale = item.lang; // it doesn't work
};

What do I need to import inside my <script setup>?
import { useI18n } from "vue-i18n"; ?

Which function to use?
tested with useI18n().locale = 'en'; but it doesn't work