If you want to customize a checklist, it's easy.
Select the checklist you want to modify.
Tap the Plus sign in the bottom right corner.
Once you tap the plus sign you are in edit mode. Note the 3 dots next too the items. Don't tap on them, tap on the actual names of the items.
You can drag items to reorder their importance to you, tap them to delete or edit the field, or rename the list by tapping the pencil at the top.
Once you tap on an item, a box will open that allows you to edit. If you tap on the wrong item just tap the "X " to close the window. Once you have edited to your liking, save task and your list will refresh!