You update the system software through System Settings → System → System Update . The Switch downloads and installs firmware updates automatically when connected to the internet.
Unlike older consoles (PlayStation, Game Boy Advance, etc.), modern Switch emulators like and yuzu don't require a single "bios.bin" file. Instead, they need two components: bios nintendo switch
The actual operating system files (the Horizon OS) that handle system functions, fonts, and audio decoding. You update the system software through System Settings
Here is the high-level workflow (assuming you have Hekate—the bootloader manager): Game Boy Advance
Ensure that you didn't just paste the firmware files into a random folder. Use the emulator's native "Install Firmware" UI path so it can unpack the components into its internal system directory structure.