How do I add or remove the 'X questions to go' message on the submit button?

You can toggle the "X questions to go" message on or off (default: off) for your form by going to Theme & Appearance → UI Elements → Submit Button.

Screenshot of the toggle, "Displays 'X questions to go' message''

The “X questions to go” counter is used to help the submitter track their progress on completing your form. It also ensures that they don’t miss any questions.

Screenshot of a partially-filled form. The text "2 questions to go" appears (instead of "Submit") in the button after the questions.

Gotchas

If you have the "X questions to go" message enabled, any total on the form won't display until all required questions answered.