Why do things look fuzzy/pixelated on my screen?
The display resolution that is configured may not be the correct one for your screen. To solve this:
Open the Activities overview and start typing Displays.
Click Displays to open the panel.
Try some of the Resolution options and select the one that makes the screen look better.
When multiple displays are connected
If you have two displays connected to the computer (for example, a normal monitor and a projector), the displays might have different optimal, or native, resolutions.
Using Mirror mode, you can display the same thing on two screens. Both screens use the same resolution, which may not match the native resolution of either screen, so the sharpness of the image may suffer on both screens.
Using Join Displays mode, the resolution of each screen can be set independently, so they can both be set to their native resolution.