注册成功后跳转到起始页

如何解决注册成功后跳转到起始页

我的网站上有一个小型登录系统。我希望用户在成功登录后被重定向到主页。经过多次尝试，各种可能性，我仍然没有成功。

这是我的登录脚本：

            <?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>
                                <a href="index.PHP" class="btn btn-yale-blue mb-50">Continue</a>
                            <?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
                    }
                }
            ?>

我已经进行了这些尝试：

header("Location: index.PHP");
exit;

header("Location: index.PHP");

header('Location: login.PHP?redirect=index.PHP');

我真的很期待得到答案，因为我已经在解决方案上纠结了几个小时！