In order to edit a prayer you shared, you can go to the prayer, tap the three dots and select Edit prayer in the pop-up menu that appears. This is different from updating a prayer, which adds a new prayer update above your existing prayer request.
This is different than an update, which adds your update text in addition to your original prayer request. On how to update a prayer, read this article: How to update a prayer. You also cannot edit a prayer once it has an update. Only the author of the prayer can update it.
