I am having an access problem to some files and directories that I have tracked down to the group assigned to access them. WHen I manually change the name of the group in the properties/permissions menu for a directory from the default setting (MyGroup) to www-data used by my Drupal Website, the directory error messages I get are gone. There are a large number of files and directories that require this change. If believe using chmod will change the owner which is set correctly and being new to Ubuntu, I am reluctant to experiment without a better understanding of how owner and groups work in the permissions settings.
You can use
to set user and group ownership where
There is also
if you do not need to touch the user permissions and only need to set the group.
Oh and you can check what group a user belongs to with