Take our apologies that you faced any inconvenience using our theme!
It would be better to numerate your questions next time to avoid misunderstanding. Ok?
1) If you installed the Elementor demo you need to use Elementor builder previously enabled for the static blocks https://xstore.helpscoutdocs.com/article/47-static-blocks to edit Static block content. So, to edit footer just go to Static Blocks > edit Footer block using elementor.
2) The same for the mega menu. Just edit items https://prnt.sc/10i4nbh and change title and links to what you need
3) To change the permalinks go to Settings > Permalins > choose the way you need https://prnt.sc/10i4oie
