Read the following paragraph.
When you use a computer, make sure the screen is in the right place for you. If someone was using the computer before you, the screen might be in the right place for that person. But the screen might be too high or too low for you. Put the screen in a good position for you before you start to work.
If you add you own ideas to what you have read, you can figure out that
a
someone moved your computer screen and you have to fix it.
b
you need to move the computer screen so you can see it clearly