LXQT settings with KWIN - window manager not open

[geminifrench]

I try to configure LXQT and KWIN.

In the "configuration center" (menu -> Preferences -> LXQT settings -> LXQT configuration center ), i click twice on "window manager" icon. But nothing is happening.
Same thing if i double clik on "window manager tweaks".

I want to reduce the title bar of windows applications.

Someone has encounter this problem ?
Is there a method to open or configure the window manager in terminal (or other method) to reduce the windows title bar and configure in general the title bar?

[geminifrench]

i have hack the problem with install "kde system settings"
soluce here : TUTORIAL - complete DEBIAN INSTALL with 4G working

But not solve the too big thickness of title bar (i search with "window decoration" stuff)