In my case I'm using lightdm by default and autologin settings can be set from lightdm configuration.

1. Open terminal and run command:

   sudo nano /etc/lightdm/lightdm.conf
   

2. Scroll down and find [SeatDefaults] or [Seat:*] and add these lines below, don't forget to change the autologin-user with your username:

   autologin-guest=false
   autologin-user=brama
   autologin-user-timeout=0
   

3. Save then reboot your computer.