Apply conditional formatting using VBA

Another approach would be:

Sub Enter_Formula_Multiple_Worksheets()
Dim ws As Worksheet
Dim rng As Range
Dim lr As Long, Col As Long
Dim Formula As String
Dim ColRng As Range
Formula = "IF(A5<>SUM(E5:G5),""Caution!"",""ok"")"
Dim ColNameFormula As String
Dim ColNameCopyingDown As String

ColNameFormula = InputBox("Choose column letter where the formula will be entered", "Set Column Letter for formula")
If ColNameFormula = "" Then
MsgBox "You didn't select a column letter.", vbExclamation
Exit Sub
End If

ColNameCopyingDown = InputBox("Choose column letter to determine the number of copying down actions of the formula", "Set Column Letter")
If ColNameCopyingDown = "" Then
MsgBox "You didn't select a column letter.", vbExclamation
Exit Sub
End If

Application.ScreenUpdating = False
For Each ws In Worksheets
    Select Case ws.Name
         Case "1_Index", "2_Auswertung", "3_Gesamtliste", "X_Sorting", "Y_ColumnHeader", "Z_Requirements"
        
        Case Else
            lr = ws.Cells(Rows.Count, Range(ColNameCopyingDown & 1).Column).End(xlUp).Row
            If lr > 4 Then
                ws.Range(ws.Cells(5, Range(ColNameFormula & 1).Column), ws.Cells(lr, Range(ColNameFormula & 1).Column)).Formula = "=" & Formula
            End If
            Set ColRng = ws.Range(ws.Cells(5, Range(ColNameFormula & 1).Column), ws.Cells(lr, Range(ColNameFormula & 1).Column))
            For Each cell In ColRng
                If cell.Value = "Caution!" Then
                    cell.Interior.Color = RGB(220, 17, 17)
                    cell.Font.Color = RGB(255, 255, 255)
                End If
            Next cell
    End Select
    lr = 0
Next ws
Application.ScreenUpdating = True
End Sub

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@shums

That is not conditional formatting but applying the cell interior color and form color explicitly. And the formatting done this way will remain even if the string returned by the formula gets changed.

But you never know, asker is smart enough to tweak all the codes as per his liking as he did in his last question and accepted your answer as an accepted one though he continued with the answer provided by me. :)

Also I am curious to know how did he tweak your last solution as per his requirement. :)

Oops. Oh Yes Neeraj, you are right.

Thanks for sharing.

Andreas, please ignore my code.

Hi Neeraj,

thank you very much for your quick and professional  help. I am afraid to tell you that your code throws an error message on column 36 (Runtime error 9, Index outside array).

As for your comments on the points awarding of my last question,

I will get back later this evening. Again, thank you very much for your great and professional help. I really appreciate it. The same applies to Shums

Andreas,

Try below:

Sub Enter_Formula_Multiple_Worksheets()
Dim ws As Worksheet
Dim rng As Range
Dim lr As Long, Col As Long
Dim Formula As String
Dim ColRng As Range
Formula = "IF(A5<>SUM(E5:G5),""Caution!"",""ok"")"
Dim ColNameFormula As String
Dim ColNameCopyingDown As String

ColNameFormula = InputBox("Choose column letter where the formula will be entered", "Set Column Letter for formula")
If ColNameFormula = "" Then
MsgBox "You didn't select a column letter.", vbExclamation
Exit Sub
End If

ColNameCopyingDown = InputBox("Choose column letter to determine the number of copying down actions of the formula", "Set Column Letter")
If ColNameCopyingDown = "" Then
MsgBox "You didn't select a column letter.", vbExclamation
Exit Sub
End If

Application.ScreenUpdating = False
For Each ws In Worksheets
    Select Case ws.Name
         Case "1_Index", "2_Auswertung", "3_Gesamtliste", "X_Sorting", "Y_ColumnHeader", "Z_Requirements"
        
        Case Else
            lr = ws.Cells(Rows.Count, Range(ColNameCopyingDown & 1).Column).End(xlUp).Row
            If lr > 4 Then
                ws.Range(ws.Cells(5, Range(ColNameFormula & 1).Column), ws.Cells(lr, Range(ColNameFormula & 1).Column)).Formula = "=" & Formula
            End If
            Set ColRng = ws.Range(ws.Cells(5, Range(ColNameFormula & 1).Column), ws.Cells(lr, Range(ColNameFormula & 1).Column))
            With ColRng
                .FormatConditions.Add xlTextString, String:="Caution!", TextOperator:=xlContains
                With .FormatConditions(.FormatConditions.Count)
                    .SetFirstPriority
                    With .Interior
                    .Color = RGB(220, 17, 17)
                    End With
                    With .Font
                    .Color = RGB(255, 255, 255)
                    End With
                End With
            End With
    End Select
    lr = 0
Next ws
Application.ScreenUpdating = True
End Sub

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Oh great Shums, this did the trick, thank you very much for your great help. :-)

I will award the points later on ... :-)

Neeraj, you wrote ... "But you never know, asker is smart enough to tweak all the codes as per his liking as he did in his last question and accepted your answer as an accepted one though he continued with the answer provided by me. :)"

It is always hard to award points. Shums answer on that specific question was correct and ok you are right, your code was the basis for my tweaking.  Again, awarding points equitably is not an easy task. Since Shum based his correct code on yours, I will award the majority of points to you. I hope I am doing everything right.

Thank you very much, Shums and Neeraj for your great help and support. I really appreciate it.

Regards, Andreas

I now decided to share the points 50:50, hope this is ok for both of you. Regards, Andreas