I’m a little confused about what you are seeing.
When you edit the post or page and save it do you see your saved values or the old values?
What values are you seeing that are old values?
Changing anything about an ACF group does not effect any posts or pages that were saved before, it will only affect new posts and pages or when you edit the old ones.
Some screen shots of some specific fields might help me understand what you’re seeing and how to fix i..
