Probably the best way is to create an option set with the most popular currency symbols, set the default at the user or account level to USD/$ and let them change it so when they see the numbers, it’s in that currency.

Note: Be careful that if Users can send each other values (like invoices), this will result in everyone seeing values in their own currency so you may need to store the currency on the User/Account as default AND on the actual Data types.

Yes you will need to change this across the app one time, but at least for now it’s dynamic.

I don’t know of any way that will allow you to change the :formattedas dyanmically now that you’ve already set up those expressions