The Apple Watch can be a great tool for keeping up with your messages on the go, but if talking into your wrist like a modern day Dick Tracy feels weird, you’re going to be limited to choosing from a list of canned responses. Fortunately, there are quite a few available and you can customize any of them to your liking by visiting the iPhone’s Apple Watch app.
To do this, go into the Messages section and tap on any of the replies listed under “Default Replies” and you can type in your own to replace the default. Entries you’ve added are shown in normal text, while default replies are grayed out. If you want to erase a custom reply and revert back to the default for that slot, you can tap to edit the entry and then hit the “X” button that appears at the right of the field to clear it out.