Ensure your GPU drivers are up to date. KiCad’s "Accelerated Canvas" uses OpenGL, which can be buggy on the default "Generic" Windows 7 drivers. Can you run KiCad 6 or 7 on Windows 7?
Projects created in 5.1 can be opened in newer versions later if you eventually upgrade your OS. Kicad For Windows 7
Completely free with no subscription or "lite" version limitations. Ensure your GPU drivers are up to date
Version 5.1.x was built specifically with Windows 7, 8.1, and 10 in mind. Kicad For Windows 7
Massive library of tutorials and forum posts specifically for the 5.1 interface.
You can find these older installers in the KiCad Windows Repository . How to Install KiCad on Windows 7