If you want to change the dwell time for a single bulletin, you can override the system dwell time by:
Editing a specific bulletin
Click on the Extras Menu
Set the toggle for Let the system decide dwell time? to No
Then input your own bulletin dwell time in seconds
If you want to change the dwell time for all the bulletins in a particular Zone:
Access the Configure Menu
Click on Zones
Edit your Zone
Select your preferred Bulletin Pace (bulletin dwell time)