Using new collections for each user

I am building an Expense Tracking app using Node.js where all the Income and Costs should get saved in a database.

My idea is to create a new collection for each registered user and save all their income/cost actions in that collection.

The things i would like to consider before writing it are:

• how do i name the collections
• Efficiency of this method
• is it even secure
• how do i save their data when they login from an another device
• can two users have the same collection name causing them to save their actions in one collection
• are there any better ways to do this

What i came up with to solve it was to make a model which takes the given company/user name to create a collection.

const mongoose = require('mongoose');
const bcrypt = require ('bcrypt');
const Schema = mongoose.Schema;

const UserSchema = new Schema({
    userName: {
        type: String,
        required: true,
        unique: true
    },
    userPass: {
        type: String,
        required: true
    },
    userEmail: {
        type: String,
        required: true,
        unique: true
    }
}, { timestamps: true });

UserSchema.pre('save', async function (next) {
    try {
        const hashed = await bcrypt.hash(this.userPass, 10)
        console.log('saved user with hashed password.')
        this.userPass = hashed
        next();
    } catch {
        next(error)
    }
})

const User = mongoose.model(userName, UserSchema);

module.exports = User;

And that collection can only be accessed by the one who has the password for that unique name.

So what i would like to ask is: Are there any better ways to do this?