uEnv.txt changes not persisting on reboot

I have a pine64 and need to fiddle with the uEnv.txt settings to get the hdmi working.
I have edited uEnv.txt in the DietPi directory but each time on reboot those settings are ovewritten.
From what I read this is the correct file to edit so why aren’t the changes persisting?

BTW I did succeed in persisting the changes the very first time I tried but after that all changes are reset on reboot.

What am I missing here?

Check this page:

https://github.com/Fourdee/DietPi/blob/master/uEnv.txt

as I wrote I am not editing the copy in /boot but in the /DietPi ramdisk so why am I having this issue?

Actually was having same issues on auyfan build and the procedure is to mount the boot partition and type ‘sync’ after editing
But with DietPi this ramdisk already mounted which I supposed was doing the same a mounting the boot parition

Could never get editing /DietPi/uEnv.txt to take

I did the same as on the ayufan image (or any with uboot and uEnv.txt)

sudo mkdir /mnt/boot
sudo mount /dev/mmcblk0p1 /mnt/boot  
sudo nano /mnt/boot/uEnv.txt
sudo sync

note: your mount mmc might be different check /dev

and that works for making changes. So why tell folks to edit /DietPi/uEnv.txt if that doesn’t persist?