How to switch to another payment gateway

I can't add Square when I'm building a jot form on your website. It's greyed out. Please explain this and what to do about it. The only one available was PayPal.

Thank you. 

Thank you for your assistance, but I didn't chose any payment provider. I
just clicked on the create a form link. It was that way by default.
I really don't understand what jot note is for when it comes to creating
forms for payment providers like Square. I can see how useful jot note is
for other forms, like feedback, etc.
How does the jot note created form connect to Square for the customer to
make a payment online??
I'd need a detailed explanation please. Thank you.
...

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If you need to create a payment form, you first need to choose a payment gateway. You can do this from the Add Form Elements tab:

After you added desiered gateway, you will need to connect to it from the right panel:

Then you configure it to your likings.

When you are done, your users will see credit card information on the form. They can enter it, and submit the form. After they do, payment will be sent to your Square account. Information about it will be saved to your JotForm account as well.

For detailed information, please click here.

Your second question has been moved to a new ticket. You can acces it on the following link:
https://www.jotform.com/answers/2589206

If you have any additional questions, please post them to the associated tickets.

Thank you for your cooperaiton.