Faced such a problem, stumbled upon (tag H1) on the pages of goods online store, which I have on the site is missing, in the appendage, to make this mistake correct. What to do how to be .
It is necessary to take measures to make it appear!

@Yuri
You can modify theme files do redefine H tags.
You can add it to header.php as easiest solution.

I tried but knocked out a mistake. probably conflicts with each other.
I need it so, the person added the ad, so the title of the ad title is h1 it should be displayed. because if you add ads and there is no h1. this is a senseless announcement.

@Yuri
In file:
oc-content/themes/patricia/item.php

Find line:
<h2><?php echo ucfirst(osc_item_title()); ?></h2>
Replace with:
<h1><?php echo ucfirst(osc_item_title()); ?></h1>

I did everything as written. but now the minuses have appeared, the title of the ad has become small and ugly. restore to that size does not work.

@Yuri
You should copy styles applied on h2 tags in theme and change it to h1
This row in style.css :
#listing #right h2

should be changed to:
#listing #right h1

Thank you! all is well.