If you are using a free trial demo account and you do not have yet a real account open it is not possible to change the base currency.
Convert your free trial demo account to a live IBKR account by selecting Open Account followed by Finish an Application on our website and logging in with your username and password. Your free trial demo account will become your paper trading account and will replicate the Base Currency of your live account.
To change the Base Currency in the live account, please see: How do I change the Base Currency for my account?
Please Note
- Once you have changed the Base Currency on your live account, changes to this setting generally are reflected the following trading day on your paper trading account.