Watchtvnow.co is described as an extension where you can supposedly watch TV online for free. Be wary because this is an adware that will attempt to commandeer your browser search and homepage to Watch TV Now. Persistent pop-up ads will appear on your screen asking for permission to subscribe to its push notifications.
The adware will then 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.
Watchtvnow.co is usually installed through bundled software without you knowing. You have to remove it immediately.