Can I tell when and who updated my database from v11 to v12 on Azure?
I believe this question was answered in the comments:


  It is indeed MS Azure (since you did not do it). They send you an email that on this day, the Azure SQL database servers will be upgraded. - Kin





  v12 has been GA since when? - Aaron Bertrand





  since July 2015 I think. You're probably right that we just ran out of time. I found this article, which seems to confirm your suspicion: – Erik


The article linked in Erik's contribution is Stopping or Postponing an upgrade to SQL Database V12.