Minorl,
While I agree that it is quite easy to change a breaker to the other phase in a panel - but if one is not familiar at all with electrical work - I will strongly caution about the DIY approach on this one. For one there is lethal voltages inside the panel and even though the main beaker is turned off, depending on the design of the panel there could still be live voltage inside the panel - in my main panel the feed coming from the meter to the main breaker are still live with the breaker in its off position.
Another one I will never forget, while an electrician apprentice back in Denmark, where I'm originally from, we were called to a vacation home to install an electrical outlet for a TV. Initially the owner had tried to install it himself, even though back there its actually again the law. Also every house is fed with three phases and neutral, 220V from neutral to each phase and 380V between the phases. He managed to get 380V on the outlet, and there was an empty TV stand in front of the outlet :-)
Good Listening
Peter