change terminal prompt

As a new Linux user, I have some questions about the terminal prompt.
I am using Ubuntu Ver. 7.04
I have read that the prompt can be changed by issuing the command "PS1=..."
while using the terminal (where ... is the desired type of prompt.
I tried this and it does work IF terminal is already in use.
There appear to be two files that initialize the prompt when terminal is started, ie. /etc/bash.bashrc and /etc/profile.
I have edited each of these two files to change the prompt to my preference, but the prompt does not change upon restarting terminal, that is - the default prompt still appears.

Question; Is there another setup or default procedure that controls the initial prompt for terminal?
It seems that the two files, "bash.bashrc" and "profile" are ignored when starting terminal.

This is not a serious problem, but my personal choice would show a different prompt.

I will certainly appreciate any educational help anyone can send my way about this situation.
Robert Ashley
<email address hidden>