How to configure headers for caching on nic.ru hosting?

Question

Nginx

The problem is that they use nginx to serve static, and it is not possible to add Cache-Control headers in the usual way (via .htaccess).
Having already read a bunch of blog posts, I found out that I need to switch the site to "manual mode", and then edit the etc/nginx/domain.com.site.conf file that appeared on FTP.
and it’s not even about how and what to register there, I also googled it, but at first I thought that I was doing something wrong, but it turns out that after restarting the server through the control panel, the changes in the config simply disappear.
so I don't know how to do it. I decided to ask here first, because judging by their forum, technical support is usually in no hurry to respond.
did anyone set up nginx EXACTLY IN RU-Center?