Q: how do I switch on automatic log in to mac book pro upon start up?

Jane Elizabeth Smith wrote:

 

I've been in both the users & groups pref and the security & privacy prefs. So I can't switch it off.

Is Filevault turned on?

Jane Elizabeth Smith wrote:

 

Hi Thanks for your quick response.  No File vault has never been switched on on this machine.

Verify in >Sys Pref>Security&Privacy>General the box is not checked for disable auto log-in

Can you unlock the Padlock to make a change?

Or you logged in as admin?

I know this may seem redundant, but please verify your fire vault is not on.

>Sys Presence>Security & Privacy>FileVault > file vault is turned off for this Disk

Jane Elizabeth Smith wrote:

 

Yes done that

There is some mention of iCloud password in this ref: My mac won't let me turn off my automatic login

If automatic login is unavailable for an account

When manual login is required, the “Automatic login” menu is dimmed or doesn't show the account name:

• If FileVault is turned on, manual login is required for all accounts. You can turn FileVault off.
• If an account uses an iCloud password to log in, manual login is required for that account. You might also see the message “A user with an encrypted home folder can't log in automatically.” When changing the account password, you can choose not to use the iCloud password.

ref:

Set your Mac to automatically log in during startup - Apple Support

Disk Utility>First Aid can be run on your Macintosh HD, 

from the Utilities menu dropdown from Recovery (command R on boot)