In a php session - php

Question

}
put returns between paragraphs
for linebreak add 2 spaces at end
italic or bold
indent code by 4 spaces
backtick escapes like _so_
quote by placing > at start of line
to make links (use https whenever possible)

Answer 1

You could have another session that stores the answers as an array, and add to it after each successful post
Something like this could work:
<?php
$totalQuestions = count($ques);
$_SESSION['answers'] = $_SESSION['answers'] ?? [];
// Get current question, default to 1
$currentQuestion = count($_SESSION['answers']) == $totalQuestions ?
$totalQuestions :
$_SESSION['answers'] + 1;
?>
<div class='questionHeader'>
<label>Question <?php echo $currentQuestion ?> of <?php echo $totalQuestions ?></label>
</div>
<br>
<div class='question'>
<?php echo $ques[$currentQuestion-1] ?>
</div>
Answer: <input type='text' id='answerOneSub' name='answerOneSub'>
<button type='submit' value='submit' name='submit'>Submit!</button>
<?php
if (isset($_POST['submit'])) {
$_SESSION['answers'][] = $_POST['answerOneSub'];
echo "<br>" . $_SESSION['answerOneSub'];
}
?>

Answer 2

You can use query param like this:
<?php
$page = 1;
if (isset($_GET["page"])) {
$page = (int)$_GET["page"];
}
$url = strtok($_SERVER["REQUEST_URI"], '?');
echo "<form method='post' action='" . $url . "?page=" . ($page + 1) . "'>";
echo "<div class='questionHeader'><label>Question [$page] of 6</label></div>";
echo "<br>";
echo "<div class='question'>" . $ques[$page - 1] . "</div>";
echo "<br>";
echo "Answer: ";
echo "<input type='text' id='answerOneSub' name='answerOneSub'>";
echo "<button type='submit' value='submit' name='submit'>Submit!</button>";
echo "</form>";
if (isset($_POST['submit'])) {
$_SESSION['answerOneSub'] = $_POST['answerOneSub'];
echo "<br>" . $_SESSION['answerOneSub'];
}