Everytime I believe I am done with a Customization… I open up Custom XML Editor and Remove anything that I know shouldn’t be there… Even opening Options during Customization Mode will secretly save all your settings and apply to everyone etc…
Before you think your done… Always Inspect / Clean Custom XML… 
Even moving the Screen on a 32in Monitor will set it to open for everyone at pixel 2010 lol… I always make sure I get those cleanup, painful but yah.