Ok...if your range is very short, check that indicator on the transmitter power. Most Syma TX's ship in high power mode, but I have seen at least once that it was in low from the factory. That will kill your range.
There are tons of YouTube videos on range mods for the transmitter antenna. Watch a few and you will see how it's done. Just search "Syma transmitter range mod" and you will find plenty of how-to's.