How can I change the header link URL in a specific page?

I have a small web magazine, and the basic site plus all the content for the first issue was set up by a web developer. Unfortunately we no longer work with them, so for issue 2 I'm trying to go it alone and add content using the pages they've already set up. For the most part it's been going fine, but there's one thing I can't figure out:

One of the features they added was to replace the site title with a custom logo on the pages for each individual article. This logo links to the table of contents for that issue instead of the home page. For Issue 1 that worked great, but now if I copy one of these pages to set up an article for Issue 2 the header still links to the Issue 1 table of contents.

If I view the page source I can see the script they used to change the default link:

<script>
$(document).ready(function() {
$("img[alt='Magazine']").parent().attr("href", "/issue-1/");
});
</script>

This looks similar to the strategy in this answer, except in that case they put the script into the footer section of Settings>Advanced>Code Injection, so I assume it applies to the whole site. I want to edit this script in a few specific pages, but I can't see any way to access it... if I go to the Page Setting>Advanced for these pages there's nothing in the code injection window. Anyone know what I'm missing? Sorry, new to Squarespace, and thanks in advance!

FYI: This is what I currently have in my Settings>Advanced>Code Injection. If I delete it then all the page-specific logos and links go back to the default title / home page link.

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script>Static.COOKIE_BANNER_CAPABLE = true;</script>