@Donoraffe Apologies for the confusion, but you can use multiple EA Accounts. The EA Account is not tied to the switch but the Nintendo account currently being used. In order to use a different one, when you first select the game to launch, it should ask which 'user' to play with, If the users are tied to separate Nintendo accounts they will connect to their own EA Accounts.
If you make a new user, when you launch the game with the user it will first ask to link or make a Nintendo account to link the user too. After if the Nintendo account is not already tied to an EA Account it will have you link or make a new EA Account to link it to. This will run separately from other accounts you may have on the switch.
I would recommend making sure the Nintendo accounts are not connected to the same EA Account, if so you may need to reach out to an EA Advisor to see what may be done about this, Also in case this has happened I would check to make sure the users on the switch have not bee linked to the same Nintendo Account.
