Automatic log-in is not working

I can't figure out why my iMac 10.6.8 no longer has me key in my password at startup. It had at one time and then stopped. There is no malware or third party apps. When I boot up in safe mode, I DO need to key in my password. I have done the correct steps in system preferences under Security with unchecking 'Disable Automatic Log-in'.

I also have an iMac 10.10.5 and that allows me to key in my password at startup.

I've been working with Apple computers since the 80s (setup our college computer lab with SEs, so awhile back), and know a bit about these computers but this has me stumped. I switched out my HDD for an SDD but that should not be an issue with this problem.

I have tried everything, reset the NVRAM, repaired disk permissions, flushed DNS cache and deleted caches (sudo dscacheutil -flushcache and ~/library/caches & /library/caches-I was grasping at straws). I did not repair disk as there were no issues.

Any ideas would be appreciated. I need to be able to have my computer password protected.

Thank you for your time!