1. Make sure that OS X Software is updated.
2. Remove Genieo if installed.
1. Use free AdwareMedic to remove adware
http://www.adwaremedic.com/index.php
Install , open, and run it by clicking “Scan for Adware” button to remove adware.
Once done, quit AdwareMedic.
or
Remove the adware manually by following the “HowTo” from Apple.
http://support.apple.com/en-us/HT203987
2. Safari > Preferences > Extensions
Turn those off and relaunch Safari.
Turn those on one by one and test.
3. Safari > Preferences > Search > Search Engine :
Select your preferred search engine.