The Transpose tool does not save files or create song sheets. The Side Bar above lists Ukefarm apps that provide that capability.
The Transpose tool is intended for exploring various keys of songs you play or want to learn. Use the Chord Entry button for entering chords. The transpose step buttons are for transposing to another key. Entering chords when the step buttons are selected will enter the wrong chords since they are not mapped directly to the keyboard.
Note: Do not copy and paste the chords to another app, they will only display as unicode characters.