I believe the bug here is that once you use System Settings > Details > Default applications for audio or video you then cannot individually change any related mime in nautilus > properties of a a/v filetype to a new default.
Test case: delete ~/.local/share/applications/mimeapps.list Open system settings > Details > default apps.. & set the default for either audio or video to some other player (Ex. video to vlc Then right click on a related filetype > properties > open with & try to set to another player, it will not do so (ex. r. click on a .mp4, try to set to Videos ** Changed in: nautilus (Ubuntu) Status: Incomplete => New -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to nautilus in Ubuntu. https://bugs.launchpad.net/bugs/1280794 Title: Can't change default "Open with" application To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nautilus/+bug/1280794/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs