Why do some questions come to the top of the active list when nothing seems to have been changed?
Example question:Old question without noticeable activity
If you look at the timeline for that question you will see an entry
bumped by community user
Some questions are occasionally "bumped" by the community user. See this meta answer
The Community user randomly bumps old, unanswered questions to bring them to the attention of users and [maybe] get them answered