Create and Update Patch Formula for Power Apps

How to update using patch in SharePoint list from edit form?

Using below patch function. but, its creating new record every time.

When I select an item from the gallery and edit it, creates a new item what’s the problem?

Patch Code:

If(DataCardValue1.Selected.Value = "Time Off",
Patch(
   LeaveRequests,
   Defaults(LeaveRequests),
   {
   LeaveID: CurrentUserID,    
   User:     DataCardValue6.Text,
   UserEmail:
   {
 Claims: Concatenate(
          "i:0#.f|membership|",
          DataCardValue3.Selected.Email // Person email
          ),
          Department: "",
          DisplayName: "",
          Email: User().Email, // Person email
          JobTitle: "",
          Picture: ""

   },

   Description: DataCardValue2.Text,
   TimeOffDate: DataCardValue22.SelectedDate,
   TimeOffFrom: DataCardValue19.Selected,
   TimeOffTo: DataCardValue20.Selected,
   TotalTimeRequested: Label23.Text
   
    }
  )
); Navigate(SucessScreen,None)

Patch(DataSource, {ID:selectedGalleryItem.ID},{Title:'UpdatedValue'});