If you need to edit a Gathering you created, click into the Gathering from the Home Page or through your Group and then click on the Gathering. Both avenues will lead you to the Gathering screen. Click on the three dots in the upper right corner, next to the Gathering's title. A small list of options will pop-up at the bottom of your screen allowing you to "Edit Details" for the Gathering and to "Cancel Gathering".

Selecting the "Edit Details" option will take you back to the same screen you used to create your Gathering. Edit away and then press "Save"!