Make also sure that if you want to use /etc/cups/client.conf that you do not have ~/.cups/client.conf, as if you have ~/.cups/client.conf, even empty, /etc/cups/client.conf will never get read.
Make also sure that if you want to use /etc/cups/ client. conf that you do not have ~/.cups/ client. conf, as if you have ~/.cups/ client. conf, even empty, /etc/cups/ client. conf will never get read.