Hi Denise,
For the flight time preferences, we only have the following settings available as seen in screenshot below of format: time of day or specific time. If selecting time of day, morning will appear by default and there are no further settings available to have evening default instead. I would recommend submitting this as a product idea within Participate > Product Ideas for our product team to consider for a future enhancement request.

------------------------------
Julia Plymack
Senior Customer Success Manager
Cvent
------------------------------