Created attachment 110054 [details] no section menubar open settings -> widget style->fine tuning and do not find menubar section KDE Frameworks 5.42.0, Qt 5.10.0 (собрана с версией 5.10.0),
This is by design. The global menu is now automatically enabled when you place a global menu applet in a panel or add the menu button to window decoration.
*** Bug 389729 has been marked as a duplicate of this bug. ***
*** Bug 394137 has been marked as a duplicate of this bug. ***
*** Bug 394636 has been marked as a duplicate of this bug. ***
This is a bad design then, because there is no way to disable this setting once enabled.
There's no need for a setting if it enables itself automatically once such an applet or decoration button is present.
Then at least update the documentation. The documentation still references this.
Burkhard, could you check comment #7?
documentation updated in master, see https://docs.kde.org/trunk5/en/kde-workspace/kcontrol/kcmstyle/index.html