[Plugin: PayPal Donations] Customize the "purpose" for different posts

I have added my “purpose” options to functions.php and got my widget and post donate buttons up and running. Now I would like to set a default option in the separate posts that are specific to that post. For example, the charity post has to have that specific charity set as the only option etc, but all options are available from the widget dropdown.

Thanks for any help.

https://www.ads-software.com/extend/plugins/paypal-donations/