This should already be the case. Just to clarify, you are getting the welcome modal popup every time you login? My suspicion is that you are using a privacy preserving browser which is delting your local storage/cookies each time you visit. Is that true?

Correct, yes, and best practice if you ask me 🙂 Could you have a flag in the user database and retrieve it alongside the password check, so you don't have to rely on cookies?