After that I tried various display drivers but there was no improvement.
The results were the same even when I used the standard Windows driver.
What I'm wondering is that when I use my PC with multiple monitors
the PC works with multiple monitors on the adjustment screen and setup screen
but when I press "G" on the adjustment screen to display a graph it no longer works as a multi-monitor and only the laptop screen is active and there is no signal input to the sub-display.
It is certain that some conditions change only when I press "G" to display the graph screen.