I phone issue in browser with voices and fullscreen

Hello
I have a problem with iPhone devices, All of my students who have Android didn’t complain, But iPhone users found issues in my exam, the Fullscreen button doesn’t work, And voices also, It comes with action by clicking a button to hair my explanation of something in the exam.
Is iPhone differs from Andriod in browser?
So, What I can do?

No answer?
please help