ok a few things.
do export PS1='.......' and u should c your prompt change. of course replace those dots with wutever u want. now, this is only for that particular bash session. if u exit or open a new terminal, it'll go back to the default. want u want to do is to edit the .bashrc file in your homedirectoy. put the line export PS1='.....' in there, there should already b an existing PS1 entry in there so just edit. now, after saving and exiting, u need to do source ~/.bashrc and your prompt will change. the last thing u need to do is to check your .bash_profile file also in your home directory and u need in there source ~/.bashrc it may b commmented out, so just uncomment it. now u should b all set