Updating users using the MikroTik CLI can be done with a single line of code assuming you know the user you want to update.
Using /user print in the CLI shows the current list of users.
/user set admin password=Password1! address=192.168.88.0/24
In this example we are changing the default admin account, setting the admin to Password1! and locking the user down to the default MikroTik Subnet used. I find that setting the Allowed Address for the default admin account is best practice to prevent it from being used for anything other than onsite work.