Spotify, Apple, and Amazon accounts have been hacked.

[GreeK]

I first noticed that on September 7th, someone had accessed my Spotify account and artificially increased the number of plays on many songs. I realized this later but managed to reset my Spotify password without any issues. After that, they accessed an unused Apple account of mine and recently attempted to access my Amazon account. I am changing the passwords of all the accounts I noticed but I feel uneasy. Why could this have happened to me and what should I do now?