Multiple currencies inside 1 Account

I would like to add multiple currency fields into the Account module

GBP default in Admin > Local

Added USD and EUR to the currencies in Admin > Currencies

Added 3 “Currency” Fields into the account module

  • Annual Revenue GPB
  • Annual Revenue USD
  • Annual Revenue EUR

In admin > studio > Accounts > Fields

There is a field called “Currency” and its data type is “Currency ID”

It is a dropdown linked to admin > currencies but can I ask what does it do?

Would I need a “Currency ID” type field for each of the custom fields I have made?