Autologin is clickable option in RaspberryPi configuration in left top corner, although only default user pi can be autologged, when disabling and again enabling this click box and before there had been another user set to autologin, then pi will be autologged after reboot.
In /usr/bin/raspi-config look for function
After then B1 - B4 specifies where autologin user is found. One is in /etc/lightdm/lightdm.conf, another in /email@example.com/autologin.conf. The second one is virtual terminal, which is important too. DO NOT change variables in /usr/bin/raspi-config, rather edit linked files and users in it.