Topic: Devise: Setting First User As Admin

I have successfully set up for my app the ability for a user who signs up to create an account at the same time. Currently, I have two models: users and accounts. In the user model I have an account_id field.

I am struggling now with how I can make this user (ie the first one who creates the account) be defaulted as the admin. I have an admin field in my users model (this is for use with ActiveAdmin which has been set up to use a single Users Model) and on the inital sign up I want it to automatically add a (true) in the admin field.

Secondly, I know there are multiple posts to figure out how the admin user can create other users (which I am still trying to get to work with Devise), but can someone guide me on the easiest way so that the other users (created by the admin) all are assigned the same account_id.

Any and all guidance would be greatly appreciated.