My guess is that you have this inside the Body placeholder. And when things are inside the Body placeholder, you don't see changes cascade across topics as you do with the Header and Footer. Think of the Body placeholder as being very similar to a piece of paper going through a copier. You make 10 copies of a form and 10 folks complete the copies. Perhaps you are asking for Name, Address and whatnot. Then later you decide you forgot to ask for email address. You change the master copy. But the first 10 are unaffected. Any copy thereafter *WILL* have an area for the email address though.
Helpful and Handy Links
At the end of each topic you will find the code for your related topics. One line will read something like:
<param name="Button" value="Bitmap:myimagename.bmp" />
You could try a multifile find and replace to change that.
Make sure you back up the project first.
See www.grainge.org for RoboHelp and Authoring tips
This worked great, but now the problem is that the Related Topics button has become static, I am unable to modify it for each topic.
Think I'll try out what Peters suggested as well.