Thank you for your question regarding your PHP settings. The php.ini file is where you can set limits in PHP, including the max_input_vars setting.
Here is a link to an article in our support center titled "How to update your local php settings."
It explains how to successfully modify your PHP settings, so you will know how to increase the max_input_vars setting.
If you have any further questions, feel free to post them below.
Sorry for the trouble with your php.ini setting. You will need to make your php.ini recursive for the change to be seen in subfolders. Please see the following article.
How can I make my php.ini file recursive ?
Once you set the recursive path you should see it work.