Edit the song and change the time signature to 3/4. In general there is no need to change barlines, but if there are more than three chords in a bar, the song will not be able to play.
Choose a playback style that works best for your song.
For example for a medium slow waltz try Country, Jazz - Ballad Even, Ballad Melodic or Long notes. Adjust the mixer for instruments that are too loud, set tempo as desired.
Specific information