This article talks about the new dirty state settings in Mx6 and also references a Project Settings to put it back to the way it worked in Mx5. That setting is marked as a ToDo in the article. Does that setting exist? https://docs.mendix.com/refguide5/dirty-state-behavior-for-mendix-6
Hmm, I wonder if this piece was intended to be part of the documentation. To my knowledge this setting never did end up in the modeler. But this topic is part of the upcoming Mx7, so in the near future you probably will see more about this topic.