Oh stimmt, sorry.
 

Option Explicit

Public Sub OK_click()

Dim TextBox1 As Double
Dim TextBox2 As Double
Dim TextBox3 As Double
Dim TextBox4 As Double
Dim Chkbx_BF As Boolean
Dim Chkbx_WF As Boolean
Dim Chkbx_WG As Boolean
Dim Chkbx_JET As Boolean

Dim i As Integer

i = 0

'   Zum Zählen der nächsten freien Spalte
    Do While Worksheets("Archiv").Cells(4 + i, 2).Value <> Empty
    i = i + 1
    Loop
   
'   Nummerierung
    Worksheets("Archiv").Cells(4 + i, 1) = i + 1
   
'   Beschriftung durch die Textboxen
    Worksheets("Archiv").Cells(4 + i, 2).Value = Person_anlegen.TextBox1.Value
    Worksheets("Archiv").Cells(4 + i, 3).Value = Person_anlegen.TextBox2.Value
    Worksheets("Archiv").Cells(4 + i, 4).Value = Person_anlegen.TextBox3.Value
    Worksheets("Archiv").Cells(4 + i, 5).Value = Person_anlegen.TextBox4.Value
    
'   Beschriftung durchs ankreuzen
        
        If Chkbx_BF = False And Chkbx_WF = False And Chkbx_WG = False And Chkbx_JET = False Then
        MsgBox "Qualifikation ankreuzen!", vbOKOnly + vbInformation, "Warnung"
        End If
        
        If Chkbx_BF = True Then
        Worksheets("Archiv").Cells(4 + i, 6) = "x"
        End If
        
        If Chkbx_WF = True Then
        Worksheets("Archiv").Cells(4 + i, 7) = "x"
        End If
        
        If Chkbx_WG = True Then
        Worksheets("Archiv").Cells(4 + i, 8) = "x"
        End If
        
        If Chkbx_JET = True Then
        Worksheets("Archiv").Cells(4 + i, 9) = "x"
        End If
            
    Unload Person_anlegen

End Sub

Public Sub Ende_Click()
    Unload Person_anlegen
End Sub

Hier habe ich es jetzt mit If-Endif versucht...
Chkbx sind die Checkboxen,