Why does YouTube delete its memory of me?

It happens every few months ...

My regular viewing builds up playlists, key words lead to things I've viewed before (plus extras), and there's that whole list of hundreds of regular stuff.

Then it all goes away.

I live in Greece so tonight it was all replaced with Greek music and tv etc etc

I changed location to UK and it presented me with a pile of UK tv clips, music that doesn't interest me etc

ffs

Why?

via International Skeptics Forum http://bit.ly/2Ih6A1e