Multiple checkboxes to populate single cell

Are you populating column D in the row that was double-clicked?

Some of your checkboxes are questions, and some are statements. I suggest you make them consistent.

This version builds the cell using the checkbox captions when the user hits the Submit button. In my test I changed the name of your button to CommandButtonSubmit, so you will need to make that change for this code to work.

Private Sub CommandButtonSubmit_Click()

   Dim Ctrl As Control
   
   ActiveCell.ClearContents
   For Each Ctrl In Me.Controls
      If TypeName(Ctrl) = "CheckBox" Then
         If Ctrl.Value Then ' 10=line break, 149=bullet
            ActiveCell = ActiveCell & Chr(149) & " " & Ctrl.Caption & Chr(10)
         End If
      End If
   Next Ctrl

   Unload Me
   
End Sub

Whose code was perfect? Are you referring to my solution or torachan's?

Also, giving you a push to get over a sticking point is one thing, but it sounds like you are asking for someone to a free project for you when you are getting paid to do this for a customer.

Here is the updated code. You still start by double-clicking in column D, but you can change that as needed.

Private Sub CommandButtonSubmit_Click()

   Dim Ctrl As Control
   Dim PageNum As Long
   Dim ReportCell As Range
   
   Set ReportCell = ActiveCell
   
   
   For PageNum = 0 To 2
   
      ReportCell.ClearContents
      For Each Ctrl In Me.MultiPage1.Pages(PageNum).Controls
         If TypeName(Ctrl) = "CheckBox" Then
            If Ctrl.Value Then ' 10=line break, 149=bullet
               ReportCell = ReportCell & Chr(149) & " " & Ctrl.Caption & Chr(10)
            End If
         End If
      Next Ctrl
      Set ReportCell = ReportCell.Offset(0, 1)
      
   Next PageNum

   Unload Me

End Sub

I didn't give an explanation but please note that UserForm multipages are numbered started at 0. Most other objects in VBA start at 1.