Your Nintendo 3DS will experience wear and tear over the course of its life. As with most electronics, the screens are particularly fragile. It is possible that scratches will develop over time, particularly on the bottom touchscreen.
How to easily fix a scratched LCD screen on your Nintendo 3DS XL!!
Here's what to do if there are scratches on one or both screens of your Nintendo 3DS:
Use a soft microfiber cloth specifically designed for electronics or glasses.
Only moisten the cloth with water.