It changed the wrong thing
Name the page and section: "On the About page, in the team section…". Restore from an earlier message to undo.
It said it made a change, but I can't see it
Check you're on the right page in the page picker.
Refresh the preview.
Ask it to check: "I still see the old heading on the home page".
It misunderstood
Break the request into smaller steps, or attach a screenshot showing what you mean.
It's taking a long time
Large requests can take several minutes. If nothing happens for a long time, refresh; failed requests don't use credits.