How do i remove hard staines off phone glass?

dDule

Hi. My mom got a new phone and i got her old one. It's a nice black Samsung Galaxy A3(2016).
I like it alot but there's a little problem that bothers me alot. You see, it is almost like brand new except one thing. He had a front glass protective screen since the time he was bought and she used a silicon back cover for the exact same time. I removed the old protective screen as she isn't really tech savy so she thought it was fine to have ripples and dots all over the screen but nevertheless, the front glass has 0 spots on it, while the back...has alot. It's weird. The silicon case is transparent but from the inside, it has a type of surface such as lines of dots all over it( pattern based). When ever i tried to clean it with alcohol, hard brushing and even dangerous acetone it would still leave marks. And these marks are not visible instantly. They ARE visible even when the back is totally cleaned, but on a much smaller note. They are mostly visible when the back is greased up from usage and when it gets wet, then it leaves small dots of water on the exact same spot where they are visible when dry. I tried everything so how the HELL do i remove these little poop-heads ?? How can i polish the black glass panel so i remove the thin layer of this "dirt" on top of it??

hyperfish

I kid you not. Try Ronson lighter fluid. I use it for lots of cleaning applications. Put a little on a soft cloth and rub the affected area before buffing with a clean soft cloth.
Take the obvious precautions when trying this.