Simple. You stopped reading to soon.

People are doing potential harmfull things to their mobiles and are not even going to invest 10 minutes of their time to answer themselves obvious questions already answered MANY MANY TIMES BEFORE. Damn.

To be sort of on topic:
The changes are temporary you do via "echo". "Echo blabla >" only write a value to some device. In this case the device is a parameter to some kernel-function. When the kernel starts these parameters have some default, which has to be overriden every start. "pmconfig" does exactly this - it is a more simple way of echoing different values to different parameters.