Most likely you are using PHP-FPM with Nginx, so you would edit the php.ini file

e.g. To change max file upload size to 100MB

Edit…
vim /etc/php5/fpm/php.ini

Set…
upload_max_filesize = 100M
post_max_size = 100M

Also add following line to http{..} block in nginx config:

http {
#...
client_max_body_size 100m;
#...
}

Source: https://rtcamp.com/tutorials/php/increase-file-upload-size-limit/

Thanks for an awesome answer!

I think I'm using fastCGI and not PHP-FPM though. Is that likely or am I completely not understanding how the system works? I followed the LEMP stack tutorial here on Digital Ocean so whatever that installs is what I'm using. Would you mind sharing what to edit if that's the case? Also, how would I check that? Sorry for such noobish questions, trying to learn a lot really fast.

Can someone help step by step To change max file upload size