How to Select a Broker Account For Trading

For manual trading

Select the account on the Chart Trading Panel in the Account Selector.
Find more info about manual trading here.

For auto trading

Select the account in Format → Strategy Properties → Auto trading tab → Broker Plug-in section
Click the gear icon to open the broker plug-in settings. If required, click Lookup to select the account.
For Interactive Brokers accounts with sub-accounts, it's required to specify the preferred account number in the Default Account field.

Note: The account should be selected for each of your auto trading strategies. This setting is individual.

Find more info about auto trading here.