You can create additional derivatives accounts from the Manage Accounts page. This can be found under the Account button on the top right of ActiveTrader under “Settings”.
Alternatively, you can click the account name dropdown on the navigation bar at the top left of the screen, select “Edit accounts” then click on" + Add new account".
You can have a total of up to 5 Gemini accounts (this includes your Primary exchange account but not your Custody account).