What do you mean trust 3? It has three feedbacks or a green trust score of 3? And no, time logged in has nothing to do with activity. Thats how many two week periods you've posted in.
Not exactly sure how trust works. But i have one positive feedback from a well trusted member.
http://i.imgur.com/EAI6nPT.pngOn the first arrow there is a 3. On the second arrow there is a +1