Сдвиг гласных , чем отличается 15 век от 16-17 вв. в произношении , как правильно произносить?

1. the tech support man asked if the customer was sure she had used the right password. the customer said that she was sure because she had seen her colleague to do it. the tech support man asked if the customer could tell him the password.the customer said that the password was five stars. 2. the customer said that she had a huge problem because a friend of her had placed a screen saver on the customer's computer, but every time she moved the mouse, it dis­appeared. 3. the tech support man asked if the customer could see the ‘ok’ button displayed in the bottom left of the screen. the customer asked the tech support man how she could see his screen from there.4. the advisor said that the  customer had spyware on his machine which was causing the problem. the customer was surprised and asked if people could see her getting dressed through the monitor.