Long-term rates (i.e. Bond yields) are set by the market in which the The Fed is a major participant but not big enough to completely control the market. This was greatly expanded under the 3 quantitative easing programs but the last of these ended almost a year ago.
Also keep in mind that the US bond market is huge - around 40 trillion dollars - with treasuries only about 1/3 of the total. Even after all the extraordinary intervention by The Fed they hold around 10% of that total. China holds less than The Fed and much of that is not is US dollar bonds.
http://www.bloomberg.com/news/articles/2015-08-25/citi-the-f...
Fed is sending mixed signals. But recent articles I've seen imply that the Fed is going to be raising rates.