comcast email password needed for imap server- after converting email to Yahoo mail

Thanks for meeting us here in our community about your email concerns, @user_qzx09d. We're happy to help. Please visit this article: https://www.xfinity.com/support/articles/yahoo-email-migration-overview to review the instructions on the Yahoo Mail transition. 

... after converting comcast email to Yahoo mail this week ... "enter user name and password for imap.comcast.net"

You no longer use the Comcast.net servers for email addresses that have been migrated to Yahoo. Instead, see the instructions under "Set up third-party email clients (like Outlook, iOS Mail, etc.)" near the bottom of https://help.yahoo.com/kb/new-yahoo-mail/SLN36803.html. You'll need to change the IMAP and SMTP servers, and the password will be the one you use to log in to https://mail.yahoo.com.