Prevent user changing pivot chart layout

[Jessica]

Is there a way to prevent user changing pivot chart layout? I have a
macro to reformat pivot chart after user change their preferred value
in the drop down box. However, if user moves the page field around, it
would break my macro. I don't want user to remove or add more filter
into the pivot chart either. Is there a way to lock layout but allow
user use pivot selection to filter data?

Thanks.

Jessica