How do we protect our digital legacy after death?

In the old days we stored our treasured memories in photo albums and paper diaries.Physical things which could be passed on in a will.But now, in our online lives our memories – our thoughts, feelings and images – are scattered to the four winds of the internet, and stored on Facebook, Twitter, Instagram, and WhatsApp.But who actually owns them?
http://www.bbc.com/news/uk-32151999