How to disable responsive design on update?

Any way to disable responsive design on updated version? I had a site all set up for my friend that looked great on both mobile and desktops. I updated to the new version after hearing that it allowed you to change the size of the slideshow more easily, but the update completely threw off the entire site design when looking at it from a mobile phone. I want the mobile and desktop experience to be the same, since there was nothing wrong with the mobile experience before.

If there is no way to do this, how do I download the previous version of the theme? I am new to this and did not backup my theme before updating. Sucks to learn the hard way.