Hidden username - Not so hidden

Webmaster,

I have experienced this myself and seen other people's post when we reply to our first response to the post we do not see the given number for our account, but it shows the screen username. The cover is blown! Now in most cases it is ok, but many cases people do not want their family members, friends, etc. to know what they have written.

How can we fix this? Also is there a way to change your given number to another number?

Thanks,
Archus