ROM Hack pokemon Black 2: how to edit the IV perfectly ?

[aos10]

hi
i have pokemon black 2
i extracted the save file from the cartridge and i want to mode the IV for a pokemon that i legitimately obtained
i used the Poke generator 3.1.13 to edit my save
when i try to mode the IV, it don't save
and they say i have to mod the IV and PID
how to do that ?
i saw this video

but it didn't help me