Explanation:
I assume you are on a single host.
To modify the .bashrc for all NEW users, you can edit/modify (with su privilege) the file
/etc/skel/.bashrc
save the file before creating new users.
Be sure to know what you're doing, and test the file before you use it host-wide.
For existing users, you can have them do the modifications/additions individually in case they have already modified their own version.