Jerome Powell has been chairman of the Federal Reserve for more than four months. But with his news conference Wednesday he finally took charge.

Mr. Powell signaled no dramatic about-face from the policies pursued under his predecessor; the Fed’s policy committee raised its main target for interest rates, as had been widely expected. By making subtle changes in c ustom , though, he put a new imprint on the institution, with potentially big implications for monetary policy and the economy.

He began his session with the news media with what he called a “plain-English” description of what the Fed had done and why, a contrast with the practice of his predecessors Janet Yellen and Ben Bernanke, both Ph.D. economists who prefaced their appearances with long prepared statements loaded with monetary policy jargon.

“The economy is doing very well,” Mr. Powell said, standing before reporters (Ms. Yellen and Mr. Bernanke both chose to sit at a desk for their post-meeting news conferences). “Most people who want to find jobs are finding them, and unemployment and inflation are low.”