Prevent sub from running - vba

Question

In sheet1 (which I've Called "MainSheet") I have a sub in my VBA script that check the values of some cells whenever a cell is changed in this sheet. (one of the main actions that will occur when a cell is changed is modifying it's color, green for Cell's with a value, red for empty cells)
But now I've got some other sub's that also change cells (in the main sheet) but in this case I don't need (and don't want) VBA to check the cells and adapt the color to their values after every cell change. (annoying when editing a large amount of cells).
(I've already tried to put this sub in the "ThisWorkbook"part of VBA instead of the Sheet1(MainSheet) part, but unfortunately this made no difference at all).
Question one: is it possible to prevent this?
I also have a correlated problem with another sub that worth mentioning in the same question I think: In this sub a new sheet is created, named and filled with text from a .txt document. Then the sheet will be saved as new workbook, and the sheet will be deleted. (The name of the sheet equals the name it will get when it's saved, and varies ever new occurrence.)
When I'm copying the .txt lines into this sheet one by one, the first sub I mentioned (the one editing cell color) is called. one of the first things happening in this sub is calling my MainSheet. When thin sub is finished the line copying sub will continue but will start pasting the lines in my Main Sheet. I tried to enter lines in this sub that select the sheet with variable name, but it keeps jumping to the MainSheet.
Question two: How do I prevent jumping to the MainSheet?
(Both questions probably could have the same solution.)
The sub that modifies the cell colours:
Private Sub Worksheet_Change(ByVal Target As Range)
Dim j As Integer
'Collor all cells green containing values, collor empty cells red.
''Starts automaticly after every cell change within this sheet
'Huidige Cell onthouden
If Not Intersect(Target, Range("A9:A29")) Is Nothing Then
On Error GoTo bm_Safe_Exit3
Application.EnableEvents = False
If Intersect(Target, Range("A9:A29")).Cells.Count > 1 Then
Application.Undo
MsgBox "Please edit one cell at a time!"
Else
Dim newVal3 As Variant
newVal3 = Target.Value
Range("A9:A29").ClearContents
Target.Value = newVal3
End If
End If
bm_Safe_Exit3:
Application.EnableEvents = True
Set myActiveCell = ActiveCell
Set myActiveWorksheet = ActiveSheet
Set myActiveWorkbook = ActiveWorkbook
Sheets("MainSheet").Select
Range("C5").Select
j = 0
Do While j < 6
If ActiveCell.Offset(0, j).Value = "" Then
ActiveCell.Offset(-1, j).Interior.Color = RGB(255, 0, 0)
Else: ActiveCell.Offset(-1, j).Interior.Color = RGB(0, 255, 0)
End If
j = j + 1
Loop
'Terug naar de voormalig active cell
myActiveWorkbook.Activate
myActiveWorksheet.Activate
myActiveCell.Activate
End Sub

Answer 1

Using .Select and .Activate is inefficient at the best of times; in a Worksheet_Change event macro it can really foul the waters.
Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo bm_Safe_Exit
Application.EnableEvents = False
If Not Intersect(Target, Range("A9:A29")) Is Nothing Then
If Intersect(Target, Range("A9:A29")).Cells.Count > 1 Then
Application.Undo
MsgBox "Please edit one cell at a time!"
'intentionally throw an error; no more code run; sent to bm_Safe_Exit
Err.Raise 0
Else
Dim newVal3 As Variant
newVal3 = Intersect(Target, Range("A9:A29")).Cells(1).Value
Range("A9:A29").ClearContents
Intersect(Target, Range("A9:A29")).Cells(1) = newVal3
End If
End If
Dim j As Integer
With Worksheets("MainSheet").Range("C5")
For j = 0 To 6
If Not CBool(Len(.Offset(0, j).Value)) Then
.Offset(-1, j).Interior.Color = RGB(255, 0, 0)
Else
.Offset(-1, j).Interior.Color = RGB(0, 255, 0)
End If
Next j
End With
bm_Safe_Exit:
Application.EnableEvents = True
End Sub
It isn't clear exactly what worksheet this is running under; I hope it isn't the MainSheet as I've used direct referencing to the cells on that worksheet.
See How to avoid using Select in Excel VBA macros for more methods on getting away from relying on select and activate to accomplish your goals.