Tor can't read directory - can't change this

Hello,
I have installed Tor on Ubuntu Server 16.04. It won't start, because the file I specified in the torrc file can't be read by Tor. I think the user that runs tor is debian-tor. Is this correct? I changed the owner of the directory with chown. It won't help. What can I do that Tor can read the directory? Now Tor won't even create a log file under /var/log/tor/log
Kind regards

chmod a+r  for torrc
chmod a+rx for /every/dir/in/path/to/torrc
chmod a+w for /var/log/tor/log

Also, ps au shows user for each process.