I have one root user, that's all.
I searched a lot, There was too many question about it and no great answer to help, so I decided to ask it here hope for a good answer to help other people too.
and I kinda curios about the reason of this problem.
If you think there is not enough information just comment what you need to know.
I have never experienced this issue, though, I always have regular user and then su -l/sudo into it and graphical apps work normally that way. Out of the reason, why don't you just use regular user and then sudo from it?
Have you tried this article from Arch wiki ? Specifically "Permanently allow root access" part.
no gksudo? so just su or sudo then?
Why Unetbootin doesn't ask me for sudo password?