how can i change it so that all my .m4v files open with quicktime and not itunes ? when i go to change it and choose the "always open with" option it only does it for that particular file, not all .m4v files.
Right click on a .m4v file and choose "Get Info". In the "Open with:" section, change iTunes to Quicktime, then click the "Change all..." button. Confirm your selection, and that's it!