Yes, you can. Please make sure there is only one base currency in your account (i.e. all denominated in USD).
Step 1: Click here to navigate to IB's main page. Log into the "Account Management" portal with your IB username and password.
Step 2: On the left menu, click "Account Settings".
Step 3: On the right hand side, look for the "Configuration" panel, and click the icon for "Base Currency".
DISCLAIMER: Screenshots in this page are taken from Interactive Brokers website, provided only as a setup guidelines, and may be changed from time to time subject to Interactive Brokers discretion. Algomerchant Pte Ltd is not responsible for any loss or damages caused by inaccuracy and misrepresentation of the information.