A) If pre-installed with Knulli
- Download latest "es-theme-knulli-updater.sh" from "symbuzzer.github.io/etk"
- Copy "es-theme-knulli-updater.sh" to "roms/tools" folder as a game rom
- From Knulli, refresh gamelist and run "es-theme-knulli-updater" from "TOOLS" collection
- It will update itself if needed

B) If installed from official store
- On your console, open "MAIN MENU > UPDATES & DOWNLOADS > THEMES"
- Go Installed tab and select "Knulli > Update"
