的外れかもしれませんが、以下のような動作でしょうか?
HTML
1<!DOCTYPE html>
2<html lang="ja">
3<head>
4 <meta charset="UTF-8">
5 <title>タイトル</title>
6</head>
7<body>
8<input type="checkbox" id="Select">
9<?php for ($i = 0; $i < 3; $i++) : ?>
10 <select name="test[<?= $i ?>]" class="test">
11 <option value="">選択してね</option>
12 <?php for ($j = 0; $j < 3; $j++) : ?>
13 <option value="<?= $j ?>"><?= $j ?></option>
14 <?php endfor; ?>
15 </select>
16<?php endfor; ?>
17<script>
18 var check = document.getElementById("Select");
19
20 function func() {
21 if (check.checked) {
22 var select = document.querySelectorAll("select[name^=test]:not(:nth-of-type(1))");
23 for (var i = 0; i < select.length; i++) {
24 select[i].selectedIndex = document.querySelector("select[name^=test]").selectedIndex;
25 }
26 }
27 }
28
29 window.addEventListener("load", func);
30 check.addEventListener("change", func);
31 document.querySelector("select[name^=test]").addEventListener("change", func);
32</script>
33</body>
34</html>
追記
HTML
1<!DOCTYPE html>
2<html lang="ja">
3<head>
4 <meta charset="UTF-8">
5 <title>タイトル</title>
6</head>
7<body>
8<input type="checkbox" id="Select">
9<?php for ($i = 0; $i < 3; $i++) : ?>
10 <select name="test[<?= $i ?>]" class="test">
11 <option value="">選択してね</option>
12 <?php for ($j = 0; $j < 3; $j++) : ?>
13 <option value="<?= $j ?>"><?= $j ?></option>
14 <?php endfor; ?>
15 </select>
16<?php endfor; ?>
17<script>
18 var check = document.getElementById("Select");
19
20 function func(e) {
21 if (check.checked) {
22 var select1 = document.querySelectorAll("select[name^=test]:not(:nth-of-type(1))");
23 for (var i = 0; i < select1.length; i++) {
24 select1[i].selectedIndex = document.querySelector("select[name^=test]").selectedIndex;
25 }
26 } else if (e.target.id === "Select") {
27 var select2 = document.querySelectorAll("select[name^=test]");
28 for (var j = 0; j < select2.length; j++) {
29 select2[j].selectedIndex = 0;
30 }
31 }
32 }
33
34 window.addEventListener("load", func);
35 check.addEventListener("change", func);
36 document.querySelector("select[name^=test]").addEventListener("change", func);
37</script>
38</body>
39</html>
HTML
1<!DOCTYPE html>
2<html lang="ja">
3<head>
4 <meta charset="UTF-8">
5 <title>タイトル</title>
6</head>
7<body>
8<input type="checkbox" id="Select">
9<?php for ($i = 0; $i < 3; $i++) : ?>
10 <select name="test[<?= $i ?>]" class="test">
11 <option value="">選択してね</option>
12 <?php for ($j = 0; $j < 3; $j++) : ?>
13 <option value="<?= $j ?>"><?= $j ?></option>
14 <?php endfor; ?>
15 </select>
16<?php endfor; ?>
17<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
18<script>
19 function func(e) {
20 if ($("#Select").prop("checked")) {
21 $("select[name^=test]:not(:nth-of-type(1))").prop("selectedIndex", $("select[name^=test]").first().prop("selectedIndex"));
22 } else if (e.target.id === "Select") {
23 $("select[name^=test]").prop("selectedIndex", 0);
24 }
25 }
26
27 $("#Select").on("change", func);
28 $("select[name^=test]").on("change", func);
29 $(window).on("load", func);
30</script>
31</body>
32</html>