The only time that Truman and Stalin ever met in person was at the Potsdam Conference. This, along with what Truman knew of Stalin's actions at Yalta and afterward, shaped the relationship between the two men.
Truman felt that Stalin was being excessively aggressive in Eastern Europe. He felt Stalin was not living up to the agreements he had made at Yalta. For this reason, he had little trust for Stalin. This feeling about Stalin was mitigated to some extent by what Truman saw of Stalin at Potsdam. He came to feel that Stalin could, at least, be dealt with. However, he did come away from the meeting extremely angry at Stalin for refusing to consider a proposal having to do with rivers in Europe. Stalin rejected the proposal before the translation was even finished.
Therefore, Potsdam did not do anything much to improve the bad impression that Truman had of Stalin from Stalin's actions in Eastern Europe.