How can I disable DirectoryIndex in Apache2.4?

Question

Apache HTTP Server

here https://stackoverflow.com/questions/21346486/how-t... they said this: "It turns out you need to disable DirectoryIndex in Apache 2.4 to get automatic indexes. When DirectoryIndex is not disabled, auto index does not work and apache sends either 403 Forbidden or 404 file not found if you are using fastcgi/php-fpm. But they didn't say which file to open to disable DirectoryIndex (Ubuntu 16.04)