What should you modify if you need to change the number of pixels that are displayed horizontally and vertically on the screen?

To change the number of pixels that are displayed horizontally and vertically on the screen, the resolution is the aspect that must be modified. Resolution refers to the dimensions of the display in terms of pixels, typically represented as width x height (for example, 1920x1080). Increasing the resolution means more pixels are displayed, resulting in a sharper and more detailed image, while decreasing the resolution will reduce the number of pixels and potentially lead to a less clear image.

Adjusting resolution directly impacts how much graphical information is shown on the screen at one time. Higher resolutions allow for more content to be displayed simultaneously and enhance the detail of images and text, while lower resolutions may appear larger but can look less detailed and more pixelated.

Other factors such as color depth, refresh rate, and scaling serve different purposes. Color depth affects how many colors can be displayed per pixel, refresh rate relates to how many times the image refreshes per second, and scaling adjusts the size of content displayed on the screen without changing the resolution. Thus, modifying the resolution itself is the appropriate action when needing to change the pixel display dimensions.