aiminv yes, that is the correct proceedure.
Managed to reproduce it on demo site: https://demo.openpanel.org:2083/php/php7.1.ini/editor
When accessed directly on that page, savings works, but when accessed from the interface there is a js error on submit.
You found a bug, and I thank you for reporting it. 🙏
As a workaround, just refresh the editor before making changes and savings will work.
I will add this to the todo list and fix in next update.