With Avada 5.7 and up, we have a useful feature to better control sidebars when in responsive mode.
Via the Sidebar Global Options, found at Avada > Options > Sidebars > Sidebar Styling, you can now set the Sidebar Responsive Order. This allows you to choose the order of the main page Content, as well as the Sidebar 1 and Sidebar 2 content, when in responsive mode. For example, you may wish to reorder the options, so that Sidebar 1 content is always displayed above normal content in responsive mode. This is achieved by a simple drag and drop interface. The settings are directly connected to the Sidebar Responsive Breakpoint, as found at Avada > Options > Responsive > Sidebar Responsive Breakpoint, so you can fine tune exactly when they kick in.
As well as setting the global order of Sidebars in responsive mode in the Global Options, there is also the option to override this on a page by page basis, by choosing the responsive order in the Avada Page Options, as shown below.