Typed correct password, but it keeps saying wrong!!!

I need to update my macOS to Mojave, so I open the App Store.

But whenever I try to log in to my apple account, it saying "An Apple ID verification code is required to sign in. Type your password followed by the verification code shown on your other devices."

So I followed the direction and typed the verification code shown on my phone, but now it is saying "Your password was entered incorrectly more than once. For your protection, you will need to retrieve it before continuing to use the App Store."

So I changed the password, but the situation is repeated endlessly....

What can I do?

Please help me!

Thanks,