What can I change on a challenge after I start it?

Open a challenge from the Challenges screen, and its ⋮ menu sits at the top of the page. It holds these choices:

• Edit changes the name, description, target and dates.
• Duplicate opens a new challenge form filled in with the same settings, which helps when you want to run the same goal again.
• Abandon marks the challenge as abandoned after you confirm, and you can still find it in your history.
• Delete removes the challenge and all of its progress after you confirm, so pick Abandon if you want to keep the record.

A completed challenge has two more choices. Share Achievement makes an image card of it, and Reopen puts it back in progress, which helps when old history finished a goal you only just set.

The same page has an Include all history switch. When it is on, the challenge also counts what you logged before its start date. A challenge that belongs to one of your Skills does not show this switch, because its start date is fixed.