' ------------------------------define this to constant somewhere
public const CancelClicked = 0
public const NextClicked = 1

'----both user form code

Option Explicit

Private m_bResult As Boolean
Property Get Result() As Boolean
    Result = m_bResult
End Property

Private Sub btnCancel_Click()
    m_bResult = CancelClicked
    Hide
End Sub
Private Sub btnNext_click()
    If Not ValidateUserInput() Then Exit Sub
    m_bResult = NextClicked
    Hide
End Sub

Private Function ValidateUserInput() As Boolean
   ValidateUserInput = False

 'if data don't fit criteria then exit function

   ValidateUserInput = True

End Function

' -------------- your module code

load UserForm4
UserForm4.Show

if UserForm4.Result = NextClicked then
  load UserForm6
  UserForm6.TextBox7.value = userForm4.TextBox1.value
  UserForm6.Show
  '  do something with values from UserForm6
  unload userForm6
end if
unload UserForm4

-------------------------
The clue is that data are initiated  and processed in parent module not
in user form directly.
Initiated after loading user form , processed after returning from .show

In general user form shouldn't interact with data which is not a part of
user form.
Everything can be done in parent module after hiding user form.

Try to not have unload me in your user form and you'll see that
everything becomes simpler.