Luckily I managed to work something out.
I created a page in my html folder .user.ini (dot-user-dot-ini). On that page I added the code:
max_input_vars = 5000; and it works so far.
I have one more question, I m not sure if i should create a new topic. Ι want the menu to be exactly like in https://www.8theme.com/demo/xstore/animals.
Is there a file I can import? I mean for the style. Cause now there is no border between the menu links, the secondary menu shows like it s on the basic menu and in general it s not like in your demo.