Open Yuzu
Go to `Emulation` > `Configure`
Select `System`
Check the currently installed firmware version
Close Yuzu
Delete the existing firmware files from Yuzu’s NAND folder
Open Yuzu again
Install the older firmware files you want to use
In Yuzu, go to `File` > `Install Files to NAND`
Select the older firmware `.zip`, `.xci`, or extracted firmware files
Wait for the installation to finish
Restart Yuzu
Verify the firmware version in `Emulation` > `Configure` > `System`
If needed, remove any leftover firmware-related files from the NAND folder before reinstalling
Make sure the firmware version matches the one required by your game or setup