I'm seeing three widgets on your home page, two in the "Home First Widget Area" widget area, and one in the "Home Third Widget Area". They're displaying as expected, with the first two in a single column and the third to the right. Moving one of the "First" area widgets into the "Home Second Widget Area" column should allow them to display in three columns.
Once you've done this, try clearing your browser's cache to ensure you're seeing the most recent version of your site with the changes.
If this is still a problem, can you post a screenshot of the Appearance -> Widgets area of your blog (with the Home widget areas expanded so we can see how they're arranged) and the resulting display on your home page? Also helpful would be your browser and browser version. Thank you!
@soloviento, I only see two widgets in the Home widget areas, one in first and one in third. They're displaying side by side, as expected. If that's not the issue, please post a screenshot and additional information following the instructions above, so we can start to troubleshoot this issue.
The "All single posts" setting refers to single Posts, and you haven't created any Posts, which is why you're not seeing the custom menu widget. You'll need to set its Visibility to specific Pages instead -- let me know if that clarifies!