Forwarding to start page after successful registration - php

Question

I have a small login system on my site. I want the user to be redirected to the home page after the successful login. After several attempts with many possibilities, I still do not succeed.
This is my login script:
<?php
if (isset($_POST["submit"])) {
require("mysql.php");
$stmt = $mysql->prepare("SELECT * FROM $accounts WHERE email = :email");
$stmt->bindParam(":email", $_POST["email"]);
$stmt->execute();
$count = $stmt->rowCount();
if ($count == 1) {
$row = $stmt->fetch();
if (password_verify($_POST["password"], $row["password"])) {
$_SESSION['username'] = $row['username'];
?>
<div class="alert alert-emerald text-center mb-50">
You have been successfully registered
</div>
Continue
<?php
} else {
?>
<div class="alert alert-red-ncs text-center mb-50">
The specified password is incorrect
</div>
<?php
}
} else {
?>
<div class="alert alert-red-ncs text-center mb-50">
An account with this email address was not found
</div>
<?php
}
}
?>
I have already had these attempts:
header("Location: index.php");
exit;
header("Location: index.php");
header('Location: login.php?redirect=index.php');
I'm really looking forward to an answer as I've been stuck on the solution for several hours now!