All circuits start with the name "The Unnamed Circuit". This is easy to change! There are two ways:
1) When you're editing the circuit just click in it's name in the upper left, this opens the settings dialog and you may change the name.
2) When you're editing a circuit you may click the little gear icon in the upper right to enter the settings menu.
Name changes are saved immediately and there is no need to press a Save or Enter button. Whatever you type is saved.