Email account remains linked to previous host servers, won't update to new provider's server.

I've updated a Thunderbird email account to a new provider, servers, per the new host, and entered my new password to view the emails. (I need to keep the existing email address, since this is for a business) When logging in, I get the message: Login to server failed. Also a failure message appears that shows it's trying to log into the previous host's servers with those servers logging out. How can I fix this?

Thanks, Kurt