Wrong font scaling on triple monitor setup

 I am running X11 on Kubuntu 21.04 and Plasma 5.21.4. When i run the "qt-unified-linux-x64-4.1.1-online.run" which is the current installer from qt.io the Installer looks like this:
Which has a way too small Font for me to read it. The cmd: "xrdb -query | grep Xft" returns this:

Xft.antialias: 1 
Xft.hinting: 1 
Xft.hintstyle: 
hintslight Xft.rgba: rgb

which to me indicates that the dpi setting does not appear to be set, and that it might be confusing either the X11 server or Qt. So i ran "xdpyinfo | grep resolution" and "xdpyinfo | grep resolution" which returned:

 resolution: 30x30 dots per inch
 dimensions: 5760x1200 pixels (4877x1016 millimeters)

which i'm not sure if it is correct since i don't know what should be put there but i run a triple monitor setup like this:

and 3*1920 matches 5760. I also checked:

• https://linuxreviews.org/HOWTO_set_DPI_in_Xorg#Qt
• https://doc.qt.io/qt-5/highdpi.html

and tried to run these export commands before running the installer:

 export QT_AUTO_SCREEN_SCALE_FACTOR 0/1/true/false #of course only one option at a time

which seems to change nothing and
 

export QT_SCALE_FACTOR 0.5/1/2

which seems to make the Window size bigger and text somewhat readable but is still very small and hard to read.