Hi catholica,
Thanks for posting a link.
I suspect your theme was tacking on an extra search icon to the menu structure automatically, but whatever code was doing that isn’t compatible with MMM. To get the theme search icon back you would need to contact your theme authors and ask them to add in compatibility with MMM – it’s not something I can do from this end sorry.
Otherwise we have a search option in Pro:
https://www.megamenu.com/documentation/search-box/
Regards,
Tom