Changing the bash prompt can be done in your .bashrc in your home directory. It is a hidden file (hence the .) so press CTRL + H to see it.

Then open it with your text editor. You need to look for PS1. That will define the look of your bash prompt.

There are so many tutorials already out there that it would just be double work. I am including a bunch of interesting links at the bottom.

Google for “linux ps1 prompt” or “bash prompt theming” or … to find even more.

Interesting links 

Bashrc generators