clean code from recorded macro

Hi guys,

I have a wkb and if I make some changes in it and then try to work at office, the hours show "h:mm". I have recorded a macro in order to set "hh:mm" for some cells.
because I have more than 50 sheets is possible ot have it ...shorter than I got it?
the sheets are named as:
"stu-2437"
"stu-567A"
"stu-700ABC"
"stu-item1" to "stu-item12"
I appreciate your help!

regards, Tim

Private Sub CommandButton7_Click()

Application.ScreenUpdating = True
   Sheets("stu-71").Select
    Range("J16:L20").NumberFormat = "hh:mm"
    Range("P16:R20").NumberFormat = "hh:mm"
    
   Sheets("stu-812A").Select
    Range("J16:L20").NumberFormat = "hh:mm"
    Range("P16:R20").NumberFormat = "hh:mm"
    
   Sheets("stu-913").Select
    Range("J16:L20").NumberFormat = "hh:mm"
    Range("P16:R20").NumberFormat = "hh:mm"
'
'

Hi tim5, try

Private Sub CommandButton7_Click()
    Dim Ws As Worksheet
    
    For Each Ws In Worksheets
        Ws.Range("J16:L20").NumberFormat = "hh:mm"
        Ws.Range("P16:R20").NumberFormat = "hh:mm"
    Next Ws
'
'
End Sub

It's going to affect every sheet in the workbook. If you only want specific sheets affected then add the do something like:

For Each Ws In Worksheets
        If Ws.Name = "stu-2437" Then
            Ws.Range("J16:L20").NumberFormat = "hh:mm"
            Ws.Range("P16:R20").NumberFormat = "hh:mm"
            End If
        Next Ws

Except now you'll have to code for each specific sheet in your workbook. You could probably use Select Case (see here).

This is not tested because I don't have your workbook but perhaps:

Dim Ws As Worksheet
    Dim i As Integer

    For Each Ws In Worksheets
        Select Case Ws.Name
        Case "stu-2437"
            Ws.Range("J16:L20").NumberFormat = "hh:mm"
            Ws.Range("P16:R20").NumberFormat = "hh:mm"
        Case "stu-567A"
            Ws.Range("J16:L20").NumberFormat = "hh:mm"
            Ws.Range("P16:R20").NumberFormat = "hh:mm"
        Case "stu-700ABC"
            Ws.Range("J16:L20").NumberFormat = "hh:mm"
            Ws.Range("P16:R20").NumberFormat = "hh:mm"
            For i = 1 To 12
            Select Case Ws.Name
            Case "stu-item" & i
                Ws.Range("J16:L20").NumberFormat = "hh:mm"
                Ws.Range("P16:R20").NumberFormat = "hh:mm"
            End Select
            Next i
        End Select
    Next Ws

hi,
I know it affects all sheets, but the range of the others sheets is outside and some of them have text!
thank you for sending me to "Select case", I think it's .... a little bit complicated for me, I'll try to "decrypt" it!

regards, Tim

edit: I see what select means...well, I have too many sheets for using it! I use the first code you provided!
I call you if I encounter problems!

If it doesn't work or you need help understanding it, just let me know.