Connecting logged-in users only to their data in Firebase

Question

Good afternoon.

I would like to know how to make the data saved by a user be only seen by him once he has logged in.

I am using Vue.js2 and Firebase. I followed this tutorial:

https://blog.logrocket.com/vue-firebase-authentication/

Everything works perfectly: new user registration, login, logout, save data. However, when a user accesses your account and clicks on the button to view your data, all data of all users appears to them. Below, follow the codes (only referring to Firebase):

Registering:

 methods: {
    submit() {
      firebase.auth().createUserWithEmailAndPassword(this.form.email, this.form.password).then(data => {
          data.user.updateProfile({
              displayName: this.form.name,
            })
           .then(() => {});
            alert('Cadastro efetuado com sucesso!')
            this.form.name = ''
            this.form.email = ''
            this.form.password = ''
        })   
       .catch((err) => {
         this.error = err.message;
        });
    },

Login

 methods: {
    submit() {
      firebase
        .auth()
        .signInWithEmailAndPassword(this.form.email, this.form.password)
        .then(() => {
          this.$router.replace({ name: "dashboard" });
        })
        .catch((err) => {
          this.error = err.message;
        });
    },
  },

Insert Data

methods: {
    salvar() {        
      this.$http.post("usuarios.json", this.usuario).child(uid).set({
           name: this.form.name 
      });
      alert('Escrito adicionado com sucesso!')
    },
  },

And finally load the data

    methods: {
        carregar(id) {
            this.$http.get("usuarios.json").then((res) => {
                this.usuarios = res.data;
            });
            this.id = id
            this.usuario = { ...this.usuarios[id] }
        }
    }

I hope that has been made clear. Thank you very much in advance.