Mobile sidebar on top

Hey marcie73,
Sorry for the late reply, as I understand what you would like to do on your shop page, in mobile, you want the sidebar on top, then the content.
Please try this code in the General Styling > Quick CSS field or in the WordPress > Customize > Additional CSS field:

@media only screen and (max-width: 767px) { 
  #main > .container_wrap_first.template-shop.shop_columns_3 > .container {
  display: flex !important; 
  flex-wrap: wrap !important; 
  }
  #main > .container_wrap_first.template-shop.shop_columns_3 > .container > main {
      order: 3 !important; 
  }
  #main > .container_wrap_first.template-shop.shop_columns_3 > .container > aside {
      order: 2 !important; 
  }
  #main > .container_wrap_first.template-shop.shop_columns_3 > .container > header {
      order: 1 !important; 
  }
  }

I don’t believe this will effect any other pages, but please check thoroughly.
After applying the css, please clear your browser cache and check.

Best regards,
Mike