When you initially create a form, you're asked to name it and give it a URL.
The form name is what appears in the list of forms under the main Forms tab in your Formstack account to identify each form and on the browser tab when the form is open in a browser:
To edit the name of your form, click to open the form from your main Forms tab. Then, just click the pencil icon next to the form name and type in a new name. After you type the name, click the save icon to the right of the text field and it will save your new form name.
OR, you can go to the Settings > General tab of your form and edit the form name in the Form Name field. After typing in the new name, click anywhere on the page to trigger the auto-save.
You will also want to edit the URL name so the correct name is shown in the link you publish.
More information on changes made to how your form URLs are displayed can be found here.