How can I found out were my ROR app is getting its ENV variables

I took over a ROR app and I have changed ENV vars in local_env.yml and in .env to point to a new MongoDB server on MongoDB Atlas and away from MLab.

However, the app is still hitting the db on MLab. I checked the computer and there were the same ENV in bash_profile, which I have changed. I then did a source ~/.bash_profile and then restart Puma but the app is still using Mlab DB which is reached via ENV[MONGO].