Search engine not working - malware?

I recently was prompted to install Adobe Reader on my MacBook Pro, so I did. I've come to the conclusion that must have been Malware. Because shortly after I did that I started getting prompted by "Advanced Mac Cleaner" that there were all these issues on my computer and that I needed to remove them. I realized that was Malware right away so I never did anything with it. At the same time, my search engine changed. I checked my preferences and it still shows as my default search engine as Google, but when I type in the search bar of Safari it starts a search with Yahoo rather than with Google. I'm not sure how to proceed from here in order to change it to searching with Google again as my default.