You should upgrade the clockworkOS to a newer version. To do that, download the 0.21 or 0.3 image from here: GameShell OS image files
To flash the image to your SD card, download Etcher from here: https://www.balena.io/etcher
Insert your SD card into your PC, start Etcher, select the downloaded image and the SD to flash it.
After flashing, insert SD back into your Gameshell and enjoy the boot 
If you use an SD card bigger than 8GB, you can use a script I made to expand the filesystem to the whole SD card. Infos on that can be found here: Expand File System
(I made it as easy as possible)
I hope that helps!