clip speed

Is it possible to 'speed up' a clip in Storyline 2?

I've got a slide where a sentence is typed into a dialogue box, but it was recorded quite slowly, taking around 15 seconds to watch the typing going in. I'd like to speed it up, so that it's viewed over maybe half that time. Any of the timing adjustments available to me just seem to cut off the typing, rather than change it's speed... 

Thanks,

P