KDE Plasma application launcher menu editing

Using kmenuedit on a KDE-Plasma 6.2.4 - KDE-FrameWorks 6.9.0 DeskTop in openSUSE Tumbleweed: I have added a sub-menu entry (QT Tools) under the menu entry Development and cut from the Development entry all QT Applications and pasted in the QT Tools sub-menu of Development. After saving, I select the application launcher surfing to the Development entry to find nothing has been updated or changed, not even the new sub-menu QT Tools is reflected. What am I doing so wrong here? I've obviously missed the boat for I'm feeling wet behind my ears and more than slightly embarrassed.