Sorry for the super late reply. Had some issues with the internet here.
Anyway, I totally appreciate all your help and for really reaching out. Thanks a lot guys!
I have already solved the problem. The reason my “update” function went wrong and updates the last option available for the dropdown was that I didn’t get the option that was selected by the user.
Should add $location = $_POST['loctn]; right after the $xcor and $ycor variables and call the $location variable for the update query instead of $locID.