Edit the file, then just restart the Peertube service.
here is what i’m editing and how:
after making the edit away from ‹ null ›, even after doing a sudo systemctl restart peertube, and also sudo system restart nginx, the webserver simply come online again
i can’t put everything in one post for some reason, but here is what i get when doing a journalctl -feu on peertube:
The error message tells you what you have to do.
Seems you forgot to change some parameters after an upgrade.
Did you upgrade recently, without restarting peertube?
hmm. no. i did a sudo systemctl restart peertube after the upgrade.
so, i kind of gave up and went back to the production guide and copied the default production guide in again from scratch from the peertube-latest folder and redid the config again from scratch, and now i was able to enter the 90MB chunk size and large uploads seem to be working now. thanks for sticking with me on through this! the cloudflare proxy seems to have been the culprit here. it’s nice that peertube has already considered such a possibility had a section waiting in the config file. cheers to the dev team on that one 
and also. thanks again!
Great to hear!