I always use the following to upgrade major versions of Graylog on my CentOS and works great
sudo rpm -Uvh https://packages.graylog2.org/repo/packages/graylog-3.3-repository_latest.rpm
sudo yum clean all
$ sudo yum install graylog-server graylog-enterprise-plugins graylog-integrations-plugins graylog-enterprise-integrations-plugins
but when I want to do minor Graylog upgrade from currently 3.3.2 to the latest 3.3.5, I always get the error that the latest is already installed.
What is the proper way to upgrade the same version?