Hello @delonghuang,
Thanks for sharing this question with the Klaviyo Community!
The behavior of the popup form closing automatically after clicking anywhere outside of the form’s body, such as on the website itself, is expected behavior. This is because users who click outside of the popup form’s body is typically an indication that the user no longer wants to engage with the form. This form behavior is also standard practice as highlighted in the following blogs:
Other workarounds to have the signup form remain on the website despite clicking outside of the form’s body would be changing the form from a popup to a flyout form. Flyout forms do not have this limitation of the form closing should a user click outside of it’s body. Alternatively, you can also custom code your own popup form utilizing HTML/CSS which offers you complete control over the customization of your form and its behaviors. If you decide to go this route we would recommend reviewing the articles below that may assist you in custom coding this form and/or reaching out any one of our knowledgeable agency partners to assist you in this endeavor.
Thanks, and have a great rest of your day!
-David