Userform displays in (MM/DD/YYY) format, when spreadsheet stores as (DD/MM/YYYY) format

Hello David

You might like to consider simplifying this. As I intimated a loop would be better used to populate your text boxes
I alos see that every time you populate them you are calling the Function MyRange. Which means that you are calling it 43 times. Which is rather a waste of time and resources.

Just create an Excel dynamic range name called 'MyRange'
=OFFSET(Plan!$A$2,0,0,COUNTA(Plan!$A:$A),1)

Create a Public Variable in the VBA

Public myrange As Range

In your Userform initialise event

Private Sub UserForm_Initialize()
    Set myrange = Sheet1.Range("MyRange")
    For Each cell In myrange
        ComboBox1.AddItem cell
    Next
End Sub

and now your ComboBox change event is

Private Sub ComboBox1_Change()
    Dim x As Long
    On Error GoTo 1
    
    For x = 1 To 7
        If x <> 7 Then
           UserForm2.Controls("TextBox" & x) = myrange.Find(ComboBox1).Offset(0, x + 1)
           Else
           UserForm2.Controls("TextBox" & x) = Format(myrange.Find(ComboBox1).Offset(0, x + 1),"dd/mm/yyyy")
        End If
    Next x

    TextBox43 = myrange.Find(ComboBox1).Offset(0, 1)
    Label1 = ComboBox1
1 End Sub