Why cannot I change the page title of the form ?

https://form.jotform.co/70453401669860

I created a form. The <title> tag is "heading". How can I edit the <title> tag?

If I understood you correctly, you want to change the page title of your form. Inside of this guide you can find how to do it:

How to Change the Page Title of the Form

If you want to change the title of your form, please check this guide:

How to Change the Title or Name of your Form

Hope this will help. Let us know if you need further assistance. 

thanks