Theme update overwrites our customizations

Hi,

I updated the Flash theme on my website this week to version 1.4.0.1.

However, the update overwrote some of the customizations on our site, such as the 404 file, as well as the files styles.css, responsive.min.css and responsive.min-rtl.css.

Further, there no longer seems to be a menu option to customize these files.

Two short questions:
– How can we make customizations from the dashboard? (Such as the defining a 404 file).
– How do we avoid updates of the theme overwriting our customizations?

Regards,

Ciarán

The page I need help with: [log in to see the link]