Did Safari just switch its settings to Yahoo?

Hi. I use Safari every day and I have for years. I am running the latest version of Yosemite and the latest version of Safari.

Today I noticed that Safari had changed its default search engine to Yahoo. It also had changed my home page to Yahoo. And it had changed the settings for new windows and new tabs to Yahoo.

I'm sure I didn't make these changes. I also didn't download any updates to Safari in the past day. So the changes must have been made automatically and without notice.

I did a quick search online and I didn't see any recent articles saying Apple had made the switch. I saw some older articles from 2014 saying Apple was planning to switch, but nothing about it happening already.

I'm surprised Apple made the switch so silently, altering Safari's settings without letting people know. I've switched my search engine back to Google.

In any case, I'm wondering if anyone knows more details about the switch. Are there other people whose settings in Safari didn't change? I'm just curious.

Thanks!