Hi JeanMagara,
As far as I know this is a known issue in Excel, and there is no perfect solution for it. One of the workaround is to record a Visual Basic for Applications macro that saves the changes that you make to your PivotChart. But you said >>my boss uses
a mac; his computer can't run my macro. << If your boss is using Mac Office 2008, this version of Office in Mac does not have VBA. But current version Office 2011, and the prior version Office 2004 do support VBA in Mac.
Now please try another workaround, >> Remove Agency from the pivot tables, and only connect the Agency Slicer to the charts. That way the data is only one series, but the slicer works to display only the data for each agency, so whatever formatting
I apply works for everything.<<
You can find this workaround from this link:
http://forum.chandoo.org/threads/chart-formatting-changes-when-using-slicer.8633/
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
Please try this method and check if it works for you and your Bosss MAC system.
Hope its helpful.
Regards,
George Zhao
TechNet Community Support