Scroll problem and Mobile menu

First of all, sorry for my spellingmistakes, but English is a foreign language for me. I was experimenting with this Adventurous theme (free) in my offline envirnmont but I seem to ran up upon two problems. 1. On my desktop computer the site works fine. But after duplicating the site on to a same offline envirnmont on my laptop, it seems that I cant scroll to the bottom of the page. After reaching the bottom by scrolling it jump right back up to the middle. 2. I want the normal menu only to appeare on a largescreen and the mobile menu on every smaller screen because the menu splits up in two rows on smaller screen. Please help me out!