You should only have to do that once per device. Choose Security & Privacy > Additional security verification.

Once you've created the password, you would use that app password to log into that older application. How Can We Create Another App Password Sign in to Office 365. If that happens, then you must create an app password. This happens when an older application does not support multi-factor authentication. You will know that you need to generate an app password if you can log into Office 365, or your York St John login details (Username and Password), but some other applications or devices do not allow you to log in with your York St John password. If you use the Outlook App on your phone, you will not have to generate an app password for your Android device. If you are using the native Mail app on your Android device, you will have to enter an app password for your phone. IT does not support other email applications, such as Mail on the iPhone or Android device. IT only supports the Outlook app on your mobile device. You only need to set up an app password if you are using a non-Microsoft email application, or an outdated version of Office. An app password is a code that gives an app or device permission to access your Office 365 account.

Enable app passwords office 365