Changing unit of downloaded .neu files

[Asho Pulsar]

I just downloaded castor wheel assy as a pro-neutral file...coz there is no part files available. In order to use it to my assembly i need to change the units from inches to mm. First i changed the units in the main assembly afterwards i thought that it would change the units of all the children parts in that assembly., but it didnt. Look at the comparison of units of main assy and the child part.





So i opened part by part, i tried to change the units immediately it vanishes after converting inches to mm. What should be the problem?