Searchinstyle on Chromebook - Help!!

Hey guys!

I purchased an HP Chromebook for school almost four years ago now and to say that it absolutely sucks is an understatement and it's gotten way worse over the last few months. About a month ago, my browser switched to Yahoo and I haven't found a way to remove it. This morning, it switched again to 'searchinstyle'. How can I go back to Chrome?

Can anybody help me please?