Mac – Does anyone know how to edit a Macro created in mobaxterm

I believe you're looking for the SlideShowNextSlide event, as documented at http://msdn.microsoft.com/en-us/library/ff745863.aspx:

Occurs immediately before the transition to the next slide. For the first slide, occurs immediately after the SlideShowBegin event.

An example is included at the MSDN link.

Per http://officeone.mvps.org/vba/run_macro_at_slide.html ("Run VBA macro at a particular slide"), there is also a OnSlideShowPageChange event, though I've not been able to find any official documentation for this on MDSN. However, per http://officeone.mvps.org/vba/events_version.html:

Occurs after showing the new slide.

This is an auto-macro and does not require any object to be declared. It is fired even when the presentation that hosts these event handlers is not in slide show mode.

You delete your whole original range. If it overlaps, it will delete overlapping cells too. To avoid that, check each cell to see if there's an overlap, e.g you can replace Range(COPYSOURCE).ClearContents by

    Dim rgLoop As Range, rgToDelete As Range
        For Each rgLoop In Range(copysource).Cells
            If Intersect(rgLoop, Range(pasterange).Resize(Range(copysource).Rows.Count, Range(copysource).Columns.Count)) Is Nothing Then
                If rgToDelete Is Nothing Then Set rgToDelete = rgLoop Else Set rgToDelete = Union(rgToDelete, rgLoop)
            End If
        Next rgLoop

        rgToDelete.ClearContents 'deletes contents keeps formatting