Hi quan3t,
The post is inside the loop. If you add the post inside the loop then your ads will be displayed in every section. If you want to customize the code then first of all create a child theme then only customize the code so that while updating to our new version your customized code will not be lost.
If you like to make direct changes in the code then each and every time while updating to new version you need to make the same customization.
It would be great if you provide your site Url too. Which blog are you using? Please clarify. If you are using the default blog then go to theme folder -> inc -> structure-> content-extension.php on line no 87 to 172. You will find this below code
if ( ! function_exists( 'ultimate_theloop_for_archive' ) ) :
Add your code inside this functions where you need your ads block. But your ads will be displayed in all blog if you add inside this functions because it’s under loop.
Better you simply add your ads in your particular post. So that only related post will display your ads.
Thank you!