The attached picture shows the password section in Options. Click Show Passwords and then right-click an entry to Edit Password.

Thanks, I found it and made the changes. But when Thunderbird went to get the messages it presented the same error message and still could not retrieve the messages.

Did you change the password on the mail provider's site before changing it in TB? TB only applies the passwords that are created elsewhere - you can't edit them in TB and expect the mail server to accept the changes.

Yes, I changed the passwords on the mail provider's site well before I changed it in TB. When this last attempt to connect the two failed I went directly to the mail provider's site to be sure I was using the correct password, which I was.

Who is the mail provider? Maybe you now have to use an app password or secure mail key to access the account through a program like TB. If none of that applies, try removing the passwords from Options, restart TB, and enter the passwords when prompted.

That worked but not exactly as you described. I tried deleting the passwords for the email accounts affected. However as soon as I clicked on the next one the one I just deleted repopulated with the password I had just deleted. Then I tried replacing the existing password with a space, shutdown TB and restarted it, replaced the space in the password field with the correct password, shutdown TB and restarted it. When I tested the download feature it worked! Thanks for your help.