Where do you configure mariadb?

I want optimise the database taking advantage of the memory on the server but when I use the link in CWP all I find is a blank file. When I add setting to this file and restart the database server it won't restart. Naturally this mean I also can't use CWP so have login via SSL to remove the setting.

same as mysql, my.cnf

That file is empty except for [server] some comments a include directive.

Each time I enter a variable the server either doesn't start or starts but gives a message about unrecognised variable.

I have 32gb and I want to use the variable

 innodb_buffer_pool_size        = 15gb