Panel Due and MKS Pi didn't communicate

I’ve built a BLV MGN Cube with a MKS Pi as Klipper Host. My other built in Hardware is a Duet2 wifi, MKS UTC (USB2Can) and a MKS THR36 as long as a PanelDue touchscreen. Everything but the PanelDue is working correctly. First I’ve tried to follow Nero 3Ds youtube video: Paneldue with Klipper- How to make it work (its easy) - YouTube

But there are a couple of things that are not seemed to exist on the prebuilt MKS Pi OS. There is no /boot/config.txt and no /boot/cmdline.txt to customise. Then I could’t figuire out how to enable the UART because sudo raspi-config didn’ work. I don’t know, if there is any other command, to get into the config to activate the the UART.

I’ve also tried it with a USB to UART adapter. There is no communication as well.

The other thing is that, when I customise the moonraker.config for the PanelDue:

After a reboot the added lines still exist, but after a power cycle the lines are missing.