Move List-box Items up & Down

To move list-box item up and down . Try below code

To move Up
Private Sub CMD_UP_Click()
    If Me.lst_selectedfields.ListCount = 0 Then Exit Sub
    If Me.lst_selectedfields.ListIndex = 0 Then Exit Sub
    
    Dim i As Long, j As Long, valtoadd As String, bl As Boolean
    bl = False
    For i = 0 To Me.lst_selectedfields.ListCount - 1
        If Me.lst_selectedfields.Selected(i) = True Then
            valtoadd = Me.lst_selectedfields.Column(0, i)
            Me.lst_selectedfields.RemoveItem (i)
            bl = True
            j = i - 1
        End If
    Next
    If bl = False Then Exit Sub
    Me.lst_selectedfields.AddItem valtoadd, j
    Me.lst_selectedfields.ListIndex = j
End Sub

To move Down

Private Sub CMD_DOWN_Click()

    If Me.lst_selectedfields.ListCount = 0 Then Exit Sub

    If Me.lst_selectedfields.ListIndex = Me.lst_selectedfields.ListCount - 1 Then Exit Sub

    Dim i As Long, j As Long, valtoadd As String, bl As Boolean

    bl = False

    For i = 0 To Me.lst_selectedfields.ListCount - 1

        If Me.lst_selectedfields.Selected(i) = True Then

            valtoadd = Me.lst_selectedfields.Column(0, i)

            Me.lst_selectedfields.RemoveItem (i)

            bl = True

            j = i + 1

        End If

    Next

    If bl = False Then Exit Sub

    Me.lst_selectedfields.AddItem valtoadd, j

    Me.lst_selectedfields.ListIndex = j

End Sub

Download the working file and use it