Hi,
Here is a link that explains the various options on how to setup OpenDNS.
You may have to check where the OpenDNS settings have been made, either in your router or in your pc.
If it is in your pc, select the Obtain DNS server automatically option and apply.
https://www.opendns.com/setupguide/
If it is in your router go to your service providers website and search for their DNS server settings to insert in your router