For my My keyword in search engines changing places 1,2,3...etc how to keep it 1st place what can i do
You will never be able to keep it in 1st place all of the time. Google is constantly showing personalized version of the SERPs, showing newly discovered URLs in top positions, etc. So your rankings will fluctuate. But the best chance of keeping your URL in the first few positions once you get there is to never stop building links to your URL. Link building is the single most influential thing you can do to get a URL to rank for a particular keyword phrase.
Agree with Canonical, keep building very strong back links for those keywords to stay on first rank, i will also recommend to use variations in anchor text to avoid penalty in search engine.
doing hard work like link exchange, articles submission, Sbm submission, blog comment posting and more for perticuler keyword..
get more and more backilinks and off page optmization...but constantly getting on first page is possible but on 1st position i dont beileve it can be forever...