change value of default template in handlebars - html

Question

i have created a template using handlebars.i need to change certain variables after of if user is logged in.
that could be done by passing the value to variable when rendering the page.
but i need to change the value of my main template that is the default layout.
here is the part of the code
<a class="nav-link nav-link-white dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
{{account or user name here}}
<i class="fas fa-chevron-down ml-2"></i>
</a>
here is my app file
var express = require('express')
var app = express()
var passport = require('passport')
var session = require('express-session')
var bodyParser = require('body-parser')
var env = require('dotenv').config()
var exphbs = require('express-handlebars')
var path = require("path") //added
app.use(express.static('public'));
//For BodyParser
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
// For Passport
app.use(session({ secret: 'key', resave: true, saveUninitialized: true })); // session secret
app.use(passport.initialize());
app.use(passport.session()); // persistent login sessions
//For Handlebars
app.set('views', './app/views')
app.engine('hbs', exphbs({ extname: '.hbs', defaultLayout: "main", layoutsDir: path.join(__dirname,"app/views") }));
app.set('view engine', '.hbs');
app.get('/', function (req, res) {
//res.send('Welcome to Passport with Sequelize');
//res.sendFile(path.join(__dirname + '/index.html')); //added
res.render('home');
});
app.get('/dashboard', function (req, res) {
res.render('dashboard');
});
//app.get('/bags', function (req, res) {
// res.render('bags');
//});
//Models
var models = require("./app/models");
//Routes
var authRoute = require('./app/routes/auth.js')(app, passport);
//load passport strategies
require('./app/config/passport/passport.js')(passport, models.user);
//Sync Database
models.sequelize.sync().then(function () {
console.log('Nice! Database looks fine')
}).catch(function (err) {
console.log(err, "Something went wrong with the Database Update!")
});
app.listen(5000, function (err) {
if (!err)
console.log("Site is live"); else console.log(err)
});
this is my route
var authController = require('../controllers/authcontroller.js');
module.exports = function (app, passport) {
app.get('/signup', authController.signup);
app.get('/signin', authController.signin);
app.post('/signup', passport.authenticate('local-signup', {
successRedirect: '/dashboard',
failureRedirect: '/signup'
}
));
app.get('/bags', authController.bags)
app.get('/productpage', authController.productpage)
app.get('/dashboard', isLoggedIn, authController.dashboard);
app.get('/logout', authController.logout);
app.post('/signin', passport.authenticate('local-signin', {
successRedirect: '/dashboard',
failureRedirect: '/signin'
}
));
function isLoggedIn(req, res, next) {
if (req.isAuthenticated())
return next();
res.redirect('/signin');
}
}