It IS easy!!
Your signature link is outranking your product page because you don't have enough inbound links, this forum gets more traffic and is better established. You'll want to be careful with using your signature for now.
Besides, you searched for the precise term,exactly as specified in the thread. It's all about relevance, authority, popularity, traffic and page rank.
It'll get better over time as you acquire more IBL's.
Good Luck.