Why is google chrome doing this?

you might have downloaded some adware that installed ask as your default search. To do this, first change the homepage. Click the chrome settings icon in the top right hand corner, the click settings. On the "Start Up" section, click "open a specific set of pages" then cick "set pages." the change the URL in the box to google.com or whatever you want. To change the default search, under the "Search" section, click the dropdown options button right next to "manage search engines," then select "google" hope this helps!