How to add digital signature to my form?

I also want to add a digital signature to my form, but it disappeared
and I can't select it any longer. Is that because of the Captha I
added?

Adding the Captcha should not be an issue. I was able to add a signature to your cloned form.

Could you please try adding the signature again? If the issue still persists - please tell which signature you are trying to add. I was also able to select all the signature fields in your form as well.

Here is the guide: How-to-Add-an-E-Signature-to-Your-Form