You want to set up your signatures on:

You can set up signatures for private domains only, but you cannot set up signatures for public domains.

The domain name is what comes after the "@" in your email address. If you have an email address jean@mybusiness.com, then you have a private domain name which is "mybusiness.com".

If you have an email address jean@gmail.com, then you have a public domain name which is "gmail.com". Public domain names are for example Gmail, Yahoo, Icloud, AOL, Hotmail.

You can't configure public domain signatures. That's why you need to have an email address with a private domain name to use the full functionality of Lodago.