send sms confirmation to users after submission

So when people submit the form, are there a service where it will send a "confirmation text" i can edit, to the user that signed up?

By default, an email will be sent to the user every time he submits the form. You can edit the content of that email by following this guide: how-to-edit-the-email-template-for-notifications-and-autoresponders

Now, if you mean you would like to send an SMS to the user, unfortunately, we do not have any widget or feature to send an SMS notification to customers. 

If your SMS provider has provided API to you, you can take advantage of our Webhook feature to send SMS using your SMS Provider's API. The following guide should help you:

Setup Webhook in JotForm: https://www.jotform.com/help/245-How-to-Setup-a-Webhook-with-JotForm 

Webhook sample script: https://www.jotform.com/help/248-Webhook-PHP-Script-Examples (Check option #2)