File names reverting

I have batch changed all the photos in an album and the event that I made it from but when I export it to a USB memory stick it changes the file names back to the original before I batch changed them. I have tried copy and paste the photos instead of using the export feature but it doesn't help.
Any ideas please.

iPhoto doesn't change the file name, only the way you see it in iPhoto. I always rename photos before i import then to iPhoto. To batch rename files use something like Name Mangler http://www.macupdate.com/app/mac/18487/name-mangler or A Better Finder Name I use this http://www.publicspace.net/ABetterFinderRename/index.html and there are a few free renamers for a Mac

Thanks for that Pomeroy.