To engage 'invisible mode' go into -user settings -account- and you'll see the box for that.
To tweak your settings go to -user settings- privacy. There are the options to change who sees what, for various aspects of your activity.
Kind of surprising that the default setting on this forum is 'everyone' - meaning, well, everyone. Most forums make their members info viewable to members only. Which is an option here to but you do have to go change those settings to make it so.
As far as I know most forums do have a fair amount of transparency when it comes to viewing other members' activities. Keeps things honest and you can learn new things, find lost friends, and stumble into interesting threads when you follow what other people are posting or reading. There's nothing to hide on a forum and none of it has to do with personal info, unless you put that info in by choice.