Has google changed algorithm Of search resultis?.I have owned two sites and optimizing both for google by using forums signature .In these days i could not see little bit inprovemend in search results .My 1st site is falling down and 2nd is not in top 500 results for keyword “watch online movies” .This keyword has low competition (by google keyword tool).I want to drive more traffic to my sites .
Please help me and suggest me that how can i get more taffic

No Google has not changed the algorithm for search results.

But google changed algorithm for page rankings, but I believe you are suffering google dance

google always change it's algorithm but no knows when

Build more quality back links for your site Definitely you get the result

google always change it's algorithm but no knows when

^^ this : one never knows when google changes the algo. To get some fast traffic try off-page seo with bookmarking, article submissions and web2.0 blogs and sites.

few months back google has did the major changes in its listing .
they were really concerned about the long tail keywords . my site was ranking for many long tail keywords but after this change i was affected by google.
for now around 3 month there is no change in its algorithm