How can I rotate the output on my screen?
Modify the /boot/config.txt and set both the following directives:
1: 90 degrees
2: 180 degrees
3: 270 degrees
If not working, please try commenting out the dtoverlay=vc4-fkms-v3d lines.
Please note that 90 and 270 degrees rotations do not work on Pi 4. Please google for alternatives.
Use mc -e /boot/config.txt via SSH or mount the SD-CARD into a running operating system and modify the file with a text editor. Also Windows works this time, because the first partition within the SD-CARD is formatted in a way that Windows understands (it understands so little).