php - How to reset/block $_POST reset by backwards of browser

one text

I'm trying to create a quiz with Form submit and $_POST.

Step 1. User should verify with e-mail first and then can play quiz.

Step 2-a. If user select correct answer, then user will be send to next-quiz-page.php.

Step 2-b. If it's wrong, then user will be send to failed-page.php.

Step 3. The status will be saved in database, when they win or lose. Therefore user who already played, can not play it again.

I did it until here with this method $_POST:

if ( isset( $_POST['quiz_start']) ) {
// quiz start
} else {
// quiz can not be loaded
}

Here is the problem: when i click a "backwards" in Step 2(next-quiz-page.php, failed-page.php) of browser, then i can back to the quiz-page again and i can play quiz again. Because the value of $_POST still are there. Of course when i submit, i will get error message because the database already has the data which is already "played".

Is there any way to reset $_POST by clicking backwards of browsers?