From everything I’ve read so far it appears that heat attracts the issues. Areas of heat produce more oil, attract more microbial activity and as a result produce seborrheic dermatitis.
Hard to say why it moves around the face. I experienced this as well. What I believe happens is that the skin in that area may become good at defending itself, so the microbes react and relocate their activity to a different region that is also viable for them.
The area around the eyes is very tricky. Currently I am using the Biom8 fairly close to the eyes, but I make sure to never actually get it in my eye as it would likely cause irritation.
Overall though I think a comprehensive approach is necessary for long term results. If you haven’t yet, I recommend you take a look at the chapter drafts for a book I’ve been working on:
It goes into significant detail about a variety of associated topics.
Hope that helps and all the best.