Trouble Getting Yahoo email into Thunderbird

Cox is migrating our emails to Yahoo. So I have several cox emails and I have migrated one to make sure there were no problems. Yup I couldn't get yahoo emails. I have been the phone with yahoo tech help and we have done several things including the app password thing that I guess Yahoo does with platforms like Thunderbird. I can send out email BUT I cannot send emails in. Funny thing is that Thunderbird is not telling me it I need to put in a new password when I am trying to download. Please understand I am not real tech savvy and I am a senior so I may be a little slower in understanding any explanations. I have loved using Thunderbird. Please help!