Is there any way to search a specific topic on this P3A forum? If there is I can't find it.

Presume you've tried a search using the magnifying glass in top bar so short answer is search using Google. Bit longer is that index for forum isn't too hot so  single term search may find what you want. If all else fails post the question. You'll get an answer plus you'll get heaps of people telling you where the threads are

Hey there, I'm afraid that the forum's search is not that great.
You can try to use "site:forum.dji.com <search term>" on Google.