On your instructables info display on youer profile, What are the topics, and how do you change them? Answered

If you click on "You" at the top of this page you will see your profile. At the bottom of your profile on the left where your picture is, you will see "edit profile". Click on that and across the top of the page that opens you will see all of the options available to you that can be used to alter your profile.

I am really not sure what you mean, what topics?