Mickey Kay on "[Plugin: Auto Menu From Pages] Menu order after update of page"

Hello,

the hierarchy of my pages is correct, but when in the same hierarchy, they're not sorted alphabetical, but on last-modified date.

Can I change this somehow?

https://wordpress.org/plugins/auto-menu-from-pages/

That is expected behavior, per this line of code:
'orderby' => 'menu_order post_modified',

That said, you should still be able to use the default menu order metabox option to individually adjust your pages, since post_modified date is just the fallback.