Dear @tikaram : When reading your answer, it seems very obvious…
It was not natural for me to understand that a kind a “demo menu” was included in the basic installation and that it would be automatically replaced by another one if I created my own menu and set it up as a primary menu.
I’m used to have control over everything in my wordpress installations and having a “non-editable default menu” was at first misleading even if I now understand why it is included.
Thank you for your fast answer. I’ll try a few things and will not hestitate to give a very positive feedback.
Dara