Speaking of defaults:
- “regular” is the default
- to change a topic from “regular” to “tracking”, one of the following must be true:
- manually switch it via the control at the bottom of the topic
- read the topic for more than four minutes
- reply to the topic
So unless you are replying, or reading the topic for quite a while (you can adjust the time interval for this in your user profiles), topics should not show as tracking.