The NewContent @Forest is set up to return results by post. It does keep defaults but only for 'time_period' and 'other' (but not the filtered forum bit)
It is context sensitive, in that if you are looking at a member, and hit view_new_content, it will return new members, at a picture...new pictures etc
It looks like you would have to 'follow' each forum you want to keep updated on and select the Just_Items_I_follow search filter. On the left hand side new_content results.
This means navigating to the forums you want to follow, and clicking the follow icon at the top of the thread list on the right. You can only 'follow' the high level forums (Train, Grow, Chill) but you can follow everything underneath these.
Unless, of course,......anyone knows different?
p.s. It could be that your pc is set not to accept cookies or they get cleared out by your browser when closing it.