If you download the full complete version of KLEO theme from the themeforest there is a KLEO child and parent theme you can download and update.
Please refer to the attached image.
You install both the parent and child theme of KLEO. But just activate the child theme and put any modifications you would like to perform on functions.php or if it is styling style.css file.
Hope it helps, i am writing this because i also faced the same situation as you are just having.
Regards,
SB Lee
