OK, I removed that table row and the only reference to userLevel in the PHP at the top of the page, and it now the userLevel does not go to "NULL" when I update the profile (makes me wonder why that column is even included on the page at all?!?)
The server behaviour now says "userLevel does not get a value" so I think that means I've done it right.
BUT... I still get the following error message at the top of the page:
Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\AKTN\admin\visitors_Profile.php:14) in C:\xampp\htdocs\AKTN\admin\visitors_Profile.php on line 66
Line 66 is:
header(sprintf("Location: %s", $updateGoTo));
AND... if I change any field (first Name, Last Name or Password), it reverts to the previous value when I click "Submit".
At this stage I'd like to do away with the Profile page completely, but the client wants staff to be able to change their passwords, so that's not an option.