@Rob
Page Builder use only column, if you choose to use 3 column you can't switch to 1 column bellow your 3,
but you can change it in your template file.
@mydatery
profile page use template file page_7.html
you can add a new column with width 100% here and it will show up bellow your X column used inside Page Builder.
You only need to code what you need (inside profile.inc.php or design.inc.php ??) and display it with page_7.html
Code ex. page_7.html (added code is green)
__include _header.html__
<div id="divUnderCustomization">
__page_main_code__
<div class="clear_both"></div>
<div class="disignBoxFirst">
<div class="boxFirstHeader">Headline: Made Online Read</div>
<div class="boxFirstHeader">Description</div>
<div class="boxContent">
Welcome all, here to create the best online community with all the little toys that you need and want.
</div>
</div>
</div>
__include _footer.html__