In my RHEL 4 system, my current bash promt is

\s - \v $
It is the default bash prompt.

However, I wish to make the bash prompt as
[\u@\h \W]#

I have tried to set bash prompt using command

PS1="[\u@\h \W]#"

But it remains till I logout the system. But when I logout the system, the bash prompt automatically changes to the default prompt.

I will appreciate any ideas from you. waiting for your suggestions in this case.