I turn off preflight but it keeps turning itself back on. How to keep it off?

I had to reinstall InDesign and trash the prefernces, so now I have to go and do all the things you need to do to make InDesign not be slow. One of them is to turn off preflght. I do that, but when I open another document, it's back on. I can't find the control that is globa.. Any tips? Thank you so much. Peace and love. #Ringo