I can't remember my password, and Mozilla says they cannot connect to my server.

No. I need my server to connect to Mozilla.

re: I can't remember my password, AOL/Verizon accounts need to use an app generated password.

You need to logon to the webmail account via a browser using normal password and then switch on 2 step verification then generate an app specific password. In Thunderbird use that app generated password for the account instead of the normal password you used to logon to server webmail account. See info: https://help.aol.com/articles/Create-and-manage-app-password

If you cannot remember the normal password, so have difficulty accessing webmail account, you should see a link - something like 'forgotten password' and follow the instructions to get access to the webmail account.