Menu / submenu on Tablet

I am working with the latest version of Hueman. I indicated a special menu for mobile, however this shows only on my phone, not on my tablet.
What can I do to show this alternative menu on a tablet ?
Furthermore, on my tablet the submenu “flashes” and the “childpages” are not shown (this should be the purpose of submenu-items, I think).
In the definitions of the pages and the menu I have defined parent and child, also the child menu option in the template.
What can I do to tackle this issue ?

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