AGAIN – Security key updated – not solved

Hi, so yesterday I opened a support for the “security key updated” this option appear under security check. I’m not talking about “Salts and Security Keys valid” this option it’s right under the one I need help.
You mark my support as solved, you are not helping me at all to solve, you just reply the same information I have when I click on info button on the plugin.

I generate the key, I want to know if I need to manually open and edit the functions.php via FTP and insert this codes. In my functions.php I don’t have any entries like AUTH_KEy…etc to update. Why this plugin needs someone to manually insert codes in my theme?? I need a better explanation in how to solve the key problem, it’s showing that this need to be solve on the plugin. I’m using the child-theme should I insert this code in the functions.php of the child theme or my main theme…. please explain better in how to proceed.