Hi.
I am trying to edit the config files and they reset every time I load my game up.
I am using
Ecology Mod 12.2-1.5.0.0
Forge 14.23.2.26611 (latest recommended release)
Mekanism (latest version although I tried without this installed with the same result)

in each file (TEPolutopnConfig.json, PollutionEffects.json and PolutionSources.json) I am changing

{
  "version": "1.4",
  "config": [
    {

to

{
  "version": "custom",
  "config": [
    {

Should I be editing anywhere else?

Thanks.

Hello, @groovyloopylou! In the new version, you should modify update.properties and set update_to properties to null to cancel file update or add |keep_entries to the end of lines to make custom entries kept after updates.