When I boot my computer, I already have to enter my password to decrypt my drive. So an additional password at the login screen (Light DM) would not be necessary.

How do I enable automatic logging in ?

I tried the "User Accounts" app, but it doesn't show me the option like here (Is it a bug ?). That is even when I unlock the app. All the answers I found to my question only apply to versions older than 12.10. screenshot of User Accounts