Hi @Anonymous ,
Could you show me more details about your settings? like the gallery's , form's,etc.
I've made a similar test and found that you need to make more settings about Mode in this scenario, you could refer this:
Set the gallery's arrow icon's OnSelect:
Set(a,"Edit");Navigate(Screen3,None)
Set the insert icon's OnSelect:
Set(a,"New");Navigate(Screen3,None)
Set the forms' DefaultMode:
If(a="New",FormMode.New,FormMode.Edit)
Set the forms' item:
Gallery1.Selected
Set the submit button's OnSelect:
If(a="Edit",Patch(table,Gallery1.Selected,Form1.Updates,Form2.Updates),
a="New",Patch(table,Defaults(table),Form1.Updates,Form2.Updates)
);
Navigate(Screen2,None)

Best regards,
Community Support Team _ Phoebe Liu