I cannot turn on god mode in protected areas

I want it to be like this: god mode on in protected areas, god mode off in unprotected areas.
How can I do this? I tried editing the areas.json and the config.yml, turned god on and off lots of times, but it never worked how I wanted it to be.

@infinity-pe Go to the config and look at # Settings for unprotected worlds and turn # Keep players from hurt? to true