You have set the chord preview to use a phrase, probably the currently selected phrase in the browser, that is why it sounds so long. You should do that only when you want to listen to a phrase with different chords in the chord selector. It is not a good idea to use this all the time. The default chord preview is shorter.
To change this open the Chord Selector, and click on the Options menu:

Select Chord+Bass in this menu and all will be fine.

