Jani Soderhall

Sorry, I don’t recall exactly what action solved it, but likely it is related to the content in each of widgets (and/or) in your footer. I would suggest you review the content of each of your widgets, ideally just deleting all content one by one (make sure you have a copy in a notepad file before, so you get put it back easily). Deleting each of the defined widgets may be even better than just erasing their content. It’s a good exercise anyway to make sure you can easily rebuild your site if you loose you widget content (after testing other templates or so).

At the time I also had a problem with the main menu not having been defined yet. Not sure it was related though. I was using the default display of the main menu, but that wasn’t enough for the mobile size menu to display (in a drop down box when the screen width is really narrow) so I manually created a main menu and assigned it. That also allowed me to sort the items and only include those that I needed.

Appearance > Customize > Header Image

The image you upload (964 x 110 px) will replace the title and the tagline.

I’m not an expert, but I had the same problem.
It may be that you have not actually defined (yourself) a menu, just used the menu that gets automatically created from your pages. That one does not seem to automatically convert to the mobile menu drop down. So, the solution for me was to create a new menu and add all the items into that menu, and then it worked. The advantage is that you can now also choose not to include all pages and organize the menu they way you want it.