You should understand what you are deploying next time. It’s your own fault for not reading the docs, analyzing how the software works, before letting it loose on your network.
The default settings I suspect cater 99% of our users usecases perfectly out of the box, which I suspect is syncing pictures of cats over the internet at no matter what cost.
You can also write a script that changes the config.xml or use the api to do it, no need to click on a lot of machines then. Just use the webinterface to change it locally and then find what options changed in the config.
For the record, the full set of considerations to keep in mind about data leakage and exposure when running Syncthing is documented here:
https://docs.syncthing.net/users/security.html
Syncthing is out of the box configured to be able to connect to almost anyone anywhere on the internet. That requires exposing a certain amount of info to the internet.
Reading docs and understanding how things work is what we all have to do before we deploy services. So, this dicussions leads to /dev/null and therefore I will close this.