Yapta will automatically name your flights for you. However, if you want to change the name here are the steps:

* Log in to your Yapta account
* Select the Trip that contains the flight you want to change
* Select the specific flight you want to rename
* Click Flight Actions dropdown
* Click  "rename this flight"
* Type the new name and click "Save"

You can also change the name of the Trip.

* Select the Trip you want to rename
* Click "Rename" button next to the trip at the top of the screen
* Type the new name and click "Save"