Access the RetroArch menu using Select+X to change core-specific settings, hotkeys, or enable rumble (if supported).
Users can customize the look via Options -> Themes or add custom themes via the ~/.emulationstation/themes directory. 5.0 Security
Source: Based on ArkOS GitHub Wiki and community documentation. If you'd like, I can:
ArkOS is typically installed by writing a .img file to a micro SD card using tools like Win32DiskImager .