How to Make Persistent System Changes (crontab, etc)

Hello, I have MyCloud EX2 Ultra which is updated to OS5, and I have followed your guideline, but my change is not persistent after reboot.

The steps I took

  1. Make the directory with command mkdir /tmp/eMMC_flash
  2. mount ubi0_0 with command mount -t ubifs /dev/ubi0_0 /tmp/eMMC_flash
  3. use vi to edit config.xml add the cron task
  4. save the xml file
  5. unmount with command umount /tmp/eMMC_flash
  6. Reboot the NAS via dashboard

Can you spot any mistake in my steps? Thanks a lot!

Thank you dswv42,
Can you please give me some advice where to look in order to make the config.xml persistent?