Important files
/etc/init.d/transmission-daemon -> SysV service
/etc/default/transmission-daemon -> run by /etc/init.d/transmission-daemon
/********/.config/transmission-daemon -> CONFIG_DIR in /etc/default/transmission-daemon
/********/.config/transmission-daemon/settings.json

User and Group running transmission-daemon
change to desired ones (e.g. USER=************) in /etc/init.d/transmission-daemon