MySearch is a forged search engine that may appear on your browser because of infection with the browser hijacker. The only way that could have happened is the installation of freeware without blocking optional offers (bundling method). A browser hijacker changes default search engine, new tab, and homepage of a browser to make users visit affiliate sites.
MySearch may have a look of a legit search engine, still there are some shady features in it. This application is usually distributed through distrusted installers that a user may have downloaded from the internet. The developers of such rogue applications are notorious for using bundling method in order to distribute their product. Bundling method is the most common in malware distribution. The developers bundle in their malware with some free software applications. We recommend you to remove MySearch as soon as possible.