Back up your SD card contents
Check your current Atmosphere version and target version
Download the older Atmosphere release you want to use
Download the matching Hekate version if required
Download the matching sigpatches only if you use them
Power off the Switch completely
Remove the microSD card from the Switch
Copy the older Atmosphere files to the root of the SD card
Replace existing Atmosphere files when prompted
Update or replace the bootloader files if needed
Keep your Nintendo folder backup safe
Reinsert the microSD card into the Switch
Boot into the payload launcher or Hekate
Launch Atmosphere
Verify the version in system settings or by checking files on the SD card
If the console fails to boot, restore your SD backup
If needed, update related homebrew apps to versions compatible with the older Atmosphere release