i want to know hw to change the units in nx
File - Utilities - Customer Defaults
Whenever you want to change something in NX for a long time, go to that place. When you change something in Customer Defaults, you need to restart NX and the change is permanent unless you change it again.
Changing anything from Preferences - .... will make only session based changes and are reset to default when you open NX another time.
if the part/model already drawn, you can use ug_convert_part.exe in the folder C:\Program Files\Siemens\NX 8.5\UGII or wherever the NX (version) installed folder. the program run in ms-dos (klik run then cmd).