How do I find out what changed the settings on my Nexus 7?

Problems...went to use my tablet and found it in Safe Mode...my weather widget was removed from my home screen and a Chrome bookmarks widget was placed on a different page without my permission...the screen saver/background was changed to the original default background.

Those are the changes I know as of now.  If it's a specific app that's doing this I would like to find out which one it is and uninstall it...right?

-concerned