How to set up the right Display Resolution - Waveshare 11.9 DSI Display

I have the problem with RPI4 2GB and 11.9 Display.
I can install the touch Display, it works but the Volumio Screen shows the wrong setting.
If I install Peppymeter for example the Meters are shown over the whole screen.
Where is my misstake…?

I have the same display and I use this, just add on your config.txt file

#"11.9 Waveshare TFT

max_framebuffer_height=1480
hdmi_group=2
hdmi_mode=87
hdmi_timings=320 0 80 16 32 1480 0 16 4 12 0 0 0 60 0 42000000 3
display_rotate=1 #1: 90; 2: 180; 3: 270

then select the propper plugin (1480x320)

Thank you. It works…
If I do the update, the display ist black…
Do you have a suggestion?

@yo2ldk gave the wrong instruction on where to put it.

Never write in /boot/config.txt as changes will be gone after an OTA.
Always place them in /boot/userconfig.txt.

After the problem with update. I installed everything new.
After reboot I’m not able to rotate the display. If I set it to 90° in the Plugin the display keeps black… And if I turn back to 0° the display keeps black.
Is the Problem the 2GB Raspi?

what is the output of:

cat /boot/userconfig.txt
cat /boot/config.txt

Now it works…
Thank you…