These variables are automatically optimizaded by Webinoly, don't take me wrong, but if you don't even know how to find a file, so it doesn't sound like a good idea trying to modify these settings.
If you still want to do it, here is the file: /etc/php/7.2/fpm/php.ini (put the correct php version you are using in the path) and then just restart PHP service to changes take effect.
Also, please I'm pretty sure you can find a lot of tutorials in Google about this topic, I highly recommend do a research before coming here and posting.
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