Do not update global fav button instead of thread's one

boards/static/js/thread_update.js

@@ -154,7 +154,7 b' function getThreadDiff() {'
             $('.metapanel').attr('data-last-update', data.last_update);
 
             if (data.subscribed == 'True') {
-                var favButton = $('.not_fav');
+                var favButton = $('#thread-fav-button .not_fav');
 
                 if (favButton.length > 0) {
                     favButton.attr('value', 'unsubscribe');

boards/templates/boards/thread_normal.html

@@ -16,9 +16,9 b''
             <form action="{% url 'thread' opening_post.id %}" method="post" class="post-button-form">
                 {% csrf_token %}
                 {% if is_favorite %}
-                    <button name="method" value="unsubscribe" class="fav">★</button>
+                    <button id="thread-fav-button" name="method" value="unsubscribe" class="fav">★</button>
                 {% else %}
-                    <button name="method" value="subscribe" class="not_fav">★</button>
+                    <button id="thread-fav-button" name="method" value="subscribe" class="not_fav">★</button>
                 {% endif %}
             </form>
             {{ opening_post.get_title_or_text }}