Search.quicksearchtool.com is a browser hijacker that will attempt to commandeer your browser search and homepage. This browser hijacker will display pop-up ads, enticing deals, discounts and coupons. Clicking these will send you to malicious websites to get money from you or infect your computer further. It may also prevent you from changing your settings back.
Search.quicksearchtool.com is usually installed through bundled software, Quick Search Tool, without you knowing. Remove it immediately.