Hi. I new to KDE. 
(I came from Cinnamon, XFCE)
I like Plasma, but some things are... confusing...

I do not like "single click" in file manager, and I wanted to change it to traditional "double click".
I spent half and hour trying to find this option in Dolphin Settings Menu. 
Then I went to Google and it told me, that I should go to System Settings -> Input Devices -> Mouse -> Double click to open files and folders... Oh, God...
It is so unnatural, unlogic... I think if user want to change the way he open files and folders in FM, he must find it in FM.

But I was even more confused, when I notice that Icons in System Settings was affected by this feature to. 
To open item is SS (like "Desktop Behavior") i need to double click it to, like a folder icon in FM!

Ok, I understand why "double click" feature placed in SS now... Because it affects not only items in FM, but other items in the system.
But, please, make two separate modes for "clicking" - one for opening files and folders in Dolphin (and place it in Dolphin Settings), other - for opening items in System Settings window (and place it in "Configure" tab that is at top of SS window)

I wish to open files and folders in FM with double click, but I want to open items in System Settings with single click.