found it.
Do this:
* YOUR-SITE.com
* Site Builder -> LATEST FORUM POSTS -> MODIFY
* Change it to this code:
{* This is the embedded template that is shown for EACH Latest Forum Posts entry on the right side *}
{capture name="template3" assign="forum_tpl"}
{literal}
{if isset($_items)}
{jrCore_module_url module="jrForum" assign="furl"}
{foreach $_items as $item}
<div class="p5">
<h3><a href="{$item.forum_topic_url}
<div class="normal" style="line-height: 12px;">
<strong>{jrCore_lang skin="jrNinja" id="45" default="Posted"}:</strong> {$item.forum_updated|jrCore_date_format:"%A %B %e %Y, %l:%M %p"}<br>
<strong>{jrCore_lang skin="jrNinja" id="46" default="By"}:</strong> <a href="{$jamroom_url}/{$item.forum_updated_profile_url}">@{$item.forum_updated_user_name}</a>
</div>
</div>
{/foreach}
{else}
<div class="center p10">
<h3>{jrCore_lang skin="jrNinja" id="26" default="No"} {jrCore_lang skin="jrNinja" id="19" default="Discussions"}!</h3>
</div>
{/if}
{/literal}
{/capture}
{* This is the END of the embedded template that is shown for EACH Top Disscusstion entry on the right side *}
<div class="blog-index-text" style="{if !jrCore_is_mobile_device()}height:225px;overflow-y:scroll;overflow-x:hidden;{/if}margin: 10px 0 0 0;padding-bottom: 10px;">
{jrCore_list module="jrForum" search="forum_post_count > 0" order_by="forum_updated desc" limit=5 template=$forum_tpl quota_check=false}
</div>
The key points is this variable
{$item.forum_topic_url} is the one that links to the latest forum post.
Prior to that it was a very long url with many parts that could in certain situations could be wrong.