New Forms will work in mobile mode "soon". Not sure when "soon" is. You can ask to be part if the Mobile Beta program or just patiently wait for hopefully not more than a month or two for GA "General Availability" of New for New Style forms working on mobile.
Until then, the default behavior is to use Legacy style form when the system detects a mobile phone device. You can see the list of forms in settings. You will need to locate the Legacy forms in your forms list and rearrange the fields or add fields there.