There are two search boxes when you’re viewing the forum.
The one at the very top searches YoYoExpert the store, the second searches the forum. Personally I think this is poor UX, there should only be one search box and it should only search the forum; if I wanted to search the store, I would visit the store and search it.
It doesn’t help that if you use keyboard navigation, then there’s no way to skip over that first search box, and for some stupid reason when the keyboard focus touches it, it opens a huge search menu that covers the whole screen and resets keyboard focus to the top of the page. So basically, the site is unusable because you can’t get past the search button. Keyboard navigation on its own should never trigger anything without enter or space being pressed… but clearly nobody even tested this.