Thank you for everyone's advice.
And I'll tell you my story.(Additional content.)
I can't easily install the avast program.
I am always installing it manually.
The reason is
If I install it automatically,
The installation of avast program cannot be completed.
(Nothing happens at the end of the program installation. The program stopped)
All programs stop after Windows 10 booting.
So I...
Always check and install all installations manually.
And then...
I re-select and install all of them in the program settings after installation.
https://youtu.be/dw5I-qgBYuQMy installation video.
(I am installing it with difficulty.
In my case, if I don't install it like this, the program won't be installed normally.)
But when I try to install a firewall program...
I had to manually check only firewall programs.
And as I told you earlier, the program was not installed.
But Windows 10... I booted it... Like a miracle, I succeeded in installing it.
(I only selected and installed firewall programs except for all of them)
Is it because I am a Korean user?
Or Windows 10 Insider. I'm guessing it's because of this.
방화벽=Firewalls (Korean words.)
https://youtu.be/dw5I-qgBYuQ?t=52I was the same without installing all programs.