A:AnswerRAM upgrade or anything requiring the back cover to me removed is not easy. If you try to do it then it may void the warranty. Geek Squad may charge you for the labor. If you think you can do it then there is a service manual as well as videos on youtube how to do it.
How to upgrade ram hdd ssd of Dell Inspiron 15 3558 3000 series 2016
https://www.youtube.com/watch?v=lHB9c1WbNyU
Inspiron 15 3558 (with optical drive) Service Manual PDF (7195 KB)
http://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_inspiron_laptop/inspiron-15-3558-laptop_service%20manual2_en-us.pdf
A:AnswerProbably because it doesn't have touch screen capabilities. I was fooled thinking that it did because I had purchased the same model previously and it did have touch screen!