There are 2 ways to access your USB drive to check and update your firmware. During compile and under Manage menu under Storage.

During Compile

When compiling your project, the final screen when you name and save your project will display the firmware version on the USB and under it, the latest version available. If there is an update available, click on the button to install the newer version.

Manage/Storage

You can also access your USB drive by opening the Manage menu under the Blue Shell and selecting Storage. Then, you must select the USB device from the Device menu. From there, it will display the firmware installed and the latest update available. Just click on the button to install the newer version.