The following options are available on the main toolbar:

• Publish - saves the form settings and updates the list to use the new form. The form becomes available to all users
• Save (under Publish) - saves the form settings but does not make it available. Use it to save your work without deploying. When you open Form Designer the next time, it will show the draft form.
• Reset (under Publish) - removes the form from the list. Does not completely delete the form, it will be reloaded next time you open Form Designer. If you decide to re-apply it to the list, just click Publish next time you load it in Form Designer.
• Preview - displays the form in a way similar (but distinct) to the actual resulting form. Use the preview to examine how the form will look like on various devices (phone, tablet, desktop).
• Export - Export the current form designer configuration to your desktop (as a form.json file).
• Import (under Export) - Import a form.json file to apply a form configuration file to the currect list's form designer. 
• Content Type - if your list contains more than one content type, choose the one to apply forms too. Each content type can have its own forms.
• Forms - choose form type[s] to apply the current form to. You apply the form only to all or only specific different form types (New, Edit, Display). The default would be to use the same form for all.
• Styles- choose one of the predefined themes or configure the general style of the form. For more information see Form Styles . Optionally specify custom CSS classes for the form. Note that you cannot use this feature to apply style to the page outside of the form, it will always be scoped to the form. Basic knowledge of CSS is required. You can also link an external CSS file by URL. The file has to reside within a document library or on CDN.
• Redirect - specify where to redirect when a form is saved and/or Closed, cancelled. You can redirect to the list view (default), to other forms or to a custom URL. Also you can specify different redirects for all forms, or for new, edit and display forms individually. 
• Toolbar - show/hide the form toolbar and control which buttons should appear on it.
• Script - configure custom scripts executed when form opens, submitted, closed or cancelled.
• Actions - configure Actions to be automatically executed on various form events. You need to configure those actions first under Actions component.
• External form - expose the form to external anonymous users either on our hosted page or on any external page, using a provided code snippet. The form will be exposed in a completely secure fashion. For more information on this see External forms