mac mail server settings

Thanks, SMWillow! That worked like a charm! For others, here's some more detail that may help. These instructions work for MacOS Monterey version 12.7.4. I suspect there are slight differences with newer MacOS.

1. To set up the one-time app password, sign into your Yahoo! web security page. Here's a link to the Yahoo! instructions for setting up a one-time password. It has an embedded link to the Yahoo! web security page. https://help.yahoo.com/kb/new-mail-for-desktop/generate-manage-third-party-passwords-sln15241.html When generating the one-time app password, Yahoo! asks for the name of your app. I typed Apple Mail.
2. Copy the one-time password.
3. Open the Apple Mail app on your computer. Click on Mail and then from the drop down box click on Add Account. Follow the prompts for adding a new Mail account, but don't use "Yahoo! Mail." Instead, set up an "Other" account. Use your Yahoo! logon credentials but use your new one-time password instead of your regular Yahoo! password.
4. You'll get a pop up box that says it failed to connect. The popup box should show that Mail used "Cox" server settings instead of Yahoo! server settings. Change the Cox server settings to the correct Yahoo! settings. The correct server settings are: for the incoming server: imap.mail.yahoo.com and for outgoing: smtp.mail.yahoo.com.
5. That worked for me.

This has been extremely frustrating. Yahoo! customer service was worthless. It's inexcusable they didn't give us these simple instructions. Thanks again SMWillow.