Q: a search engine called Open-Search has taken over my browser

Hi,

I seem to have endless beachballing and exceptionally slow navigating. Even the Apple tech support guys agree. But genius bar appts are almost impossible to get so I'm living in the 1990's version of computing.

Immediate problem is that something has taken over my web browser. I'm using Google Chrome, have been for a year now. Sometime in the last few days the problem started. When I type in a search into the Omnibox, rather than using my default search engine, which is Ecosia, it uses a search engine called Open-Search. Plus, almost every time I click on a link on a web page, it opens one of the many junk websites trying to sell me something; MacKeeper, Purifier for your Mac, Detox My Mac, Create your free website, Boiler Quotes, William Hill. . . to name only the last few. I've been doing a great deal of searching on FB for different groups in connection with my work. I've joined several but never had to install anything.

The other very odd thing is that I've had a new website made specifically for a 5 Day course I'm running. And the chap who built it, using Adobe Muse, has made changes that he can see but I can't. I've closed the browser tab and opened a fresh window, but still the changes are not visible to me.

I've checked my download history and found that the first of these odd incidents occurred the day after downloading an update for MPlayerX. So, I've deleted this download and emptied trash.

Should I clean out my cache? If so, how do I do that?

Also, when searching for details to include here, I've noticed that my storage is pretty full. And the second largest single chunk is taken up by: Other: 122.34GB. Is that normal?

Kind regards,

Miranda

Macbook Pro: 15" mid 2009

Processor: 3.06 GHz Intel Core 2 Duo

Memory: 6 GB 1067 MHz DDR3

Software  OS X 10.9.5 (13F34)

Storage HD: 15.79 GB free out of 499.25 GB

     Audio: 192.3GB Movies: 90.24GB Photos: 49.6GB Apps: 28.99GB Other: 122.34GB