Why can't I enter my responsible broker/corporation during my online renewal?

Actually, you can do so. What happened is that you may have answered "No" to the questions, "Would you like to change your responsible broker or corporation?" and/or "On renewal date, will you be engaged in real estate activities for which a California Real Estate License is required?"  If you haven't already completed your online license renewal, you can add or change your responsible broker or corporation by pressing the Back button until you come to the screens that ask these questions.  By clicking on the Yes button and following the online instructions, you will be able to effect the change.  If you've already completed your online license renewal, you can change your responsible broker or corporation by clicking on Change Responsible Broker in your Your Menu Options menu.