Addressing two DC motor controllers with two Motors each

Hello. I have the grove digital extender and I'm attempting to control two identical Grove motor controllers via i2c. I'm wondering how to address the motor controllers individually so they can be activated at different times. Currently when I have both connected to two of the i2c connections on the extender board both controllers are activated I'm assuming because they have the same i2c address. The motor controllers control two motor each so how can I control each motor on each controller separately? Do I need to use an i2c Multiplexer instead? Can I connect the motor controllers to the digital connector instead of the i2c connector?

Motor controller x2:

Seeedstudio Grove Motor Driver - Dual TB6612FNG