Could you explain the process to change my password?
Is creating a new username and password advisable?
Your guidance is requested.
With thanks.

At the top of your screen click [UserCP]
On the left column on the page that opens, click [Edit Email & Password]
Then follow instructions from there.

Change your password as often as your personal sense of security requires.
You can't change your User Name. You can request that a moderator change it by supplying a few options that you wish. Remember that many User Names are taken, so providing a few choices is useful.

What are your concerns?