Need a script to change system user

Hello,

I need a script, that I can change a system user name every month.
The new system user must have the same password.
It’s possible?
So all system user need the new login every month.
Sorry for my bad english

Yes, it’s possible. I suggest you to take a look at the following links for a start:
http://www.mikrotik.com/docs/ros/2.9/system/scripting
http://www.mikrotik.com/docs/ros/2.9/system/scheduler
http://www.mikrotik.com/docs/ros/2.8/appex/scripting1