cannot send mail username or password incorrect

Currently aol.com email, in Settings, Account, Incoming Mail Server - Host Name: imap.aol.com

Outgoing Mail Server - SMPT: smpt.aol.com

Shouldn’t Incoming and Outgoing Mail Servers be the same? Could this be my problem? Also,

What will happen if in Settings, under AOL SETTINGS - Reset All Accounts, which is currently Off, I turn it to On?

In Settings, Mail, ICLOUD Account Information - Choose a default address when sending... , Allow Sending From -

Should I select: ....... @icloud.com or. ........ @aol.com ?

In Settings, Mail - Default Account:

Should I select: iCloud, AOL, or ......@aol.com?

Please provide detailed response.

Thank you so much for your patience.