Add X-Robots-Tag to all hosts.

[rardcode]

I installed a Nginx Reverse Proxy via docker.
I would like to add X-Robots-Tag to all hosts. I tried adding the option:

add_header X-Robots-Tag "noindex, nofollow, nosnippet, noarchive";

in Advanced / Custom Nginx Configuration
but it doesn’t work.
I read that the add_header options if not included in a custom location do not work.

What custom location can I use? Or does anyone know another way to make it default?