If you have a smaller or larger screen, parts of this discussion will be meaningless for you. The finer the resolution, the more of a picture you can see at one time. That is, it makes everything smaller on your screen which gives you a bigger field of vision. Many times as you adjust your resolution higher and higher the screen starts to blink. Slight hardly noticeable blinking can cause headaches while significant blinking can drive you crazy.
Some people are more sensitive to blinking than others.
So, adjust your screen to your viewing comfort level. Click the start button usually located on the lower left of your screen. Click on Settings. Click on Control Panel. The Control Panel window will pop up.