To do this, go to Chrome settings, click on "Search engine," and select your preferred search engine as the default. If Yahoo is currently set as the default, change it to your preferred search engine. Yahoo is set as the default new tab page Sometimes, the default new tab page in Chrome can be set to Yahoo. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.