SharePoint Designer 2013 - How do I hide some fields on 'NewForm.aspx' so that they only show on 'EditForm.aspx'?

I can only open 'NewForm.aspx' in Advanced edit mode, not safe mode so struggling with finding the 'Fields' that I want to hide. Can anyone advise on how I can find these 'Fields' or perhaps a different way in which I can hide them? The form I have created is an InfoPath 2013 form, so if there is a way I can do this via InfoPath, that would be fantastic as well.

Thank you for your assistance -

Kind regards,

Janice