Date:  Mar 9, 2020

This is my /boot/config.txt looks like.

But there are few lines, we want to know how to change the value so that the screen works well even in both 3.5″ LCD screen, or the VNC display.

First, I remove all the hdmi_group and hdmi_mode here.

I added in hdmi_ignore_edid=0xa5000080 here.

This line is important.

This is because of the following.

You got the above info from here.

https://www.raspberrypi.org/documentation/configuration/config-txt/video.md#Custom%20Mode

Next, under the [all] section… I added in the hdmi_group and hdmi_mode here.  There are many many modes.

We choose DMT group.

hdmi_group=2

If you choose the CEA mode…

If you choose DMT which is

hdmi_group=2

So, all you need to do is choose the mode.  Choose something you like.