Hello,
I use a RPi 3, a IQAudio DAC+ and mentioned display (Waveshare clone) for my project.
I used this tutorial: waveshare-spotspear-3-5-touch-screen-working-with-rune-t3859.html to get my LCD-screen working.
The system first boots naturally on the HDMI screen and changes to the LCD midway. So far, everything runs as expected. Some seconds after the login screen appears, it changes back to the HDMI screen and loads the local browser. Anybody knows how to solve this?