I have set up an Ubuntu server (12.04 LTS) for samba file sharing. The problem I'm having has to do with files that I create on the server. Other users can't open them because I created them under a group that is my username, instead of the group that is allowed to view the share. Why is this? It seems that everything else is working fine. Only allowed users are able to view their share folders but they can't open anything that I create.
Because as far as the system is concerned there is no necessity to change the group ownership of the file being created away from the default group of the user creating it.
If you want file to have automatic group ownership make the directory where you are creating the files a SETGID directory.