I want to log into my Yahoo account on a new device, but I don't want to use the Account Key icon (on Windows 10 I don't see that icon), or the txt msg method. I simply want to enter my user name and password into a login screen, but I cannot find such a screen. Does it exist?
To log into your account without using the Account Key, you need to disable it. From the device you have access to your account, go to your security settings. Then in Yahoo Account Key click Manage > Disable Account Key.
If you have access to your account from the Yahoo Mail app instead, open the Menu and tap on the Key icon. Then, select Manage Account Key > Disable Account Key.