You can change everything.
Um, ok, i'll rephrase my question.
What do i have to change if there is a health bar and i want it to not decrease. (Or set its value to 9 billion)

I have a question; What other codes could we change in the text files after decompiling?
Specifically, i'm trying to find some code for values which are unknown (ex: bar of health or exp) but it...