Timeline is quite a confusing module for some, but once the main ideas are clear it's actually very powerful.
It took me quite some time to set the right permissions. I remember that it took me days to disable the right for deleting timeline updates for different membership levels. There are a lot of different settings which can conflict each other. But after that, I was able to better understand the whole permissions concept of UNA CMS, which is not so easy at the beginning.