I can be pretty indecisive. XD

It can cause problems though. Once I changed a small part of a character's backstory in something, and it took me about half a year to realise that I'd created a ridiculous plothole in doing so. I got round it eventually (after much editing), but it's not good when that sort of thing happens!

I add things but rarely do I change it. I treat my characters like people I interact with. I less of come up with back stories for them but more of find out more about them. Its their backstories that created their personality and character. Changing too much of the backstory would make them a different person.

I also add things more than I change. I think your comment describes what I do better. But there are things I have tweaked with them all. Because like, glelsey, I can be very indecisive. And I ran into the same plothole issue.

Usually it's minor details that don't matter too much to the story.