Reference ID in the Fundraising plugin. How to change

I purchased the plugin Fundraiser. Its great. However, I need to understand how I can set the REFERENCE on the paypal when it appears.
The name of the "project" is being pulled from the title. I need to set the REFERENCE area when the paypal comes up. Please look here:https://www.paypal.com/cgi-bin/webscr?cmd=_flow&SESSION=_jVphRRxOFyFf0v5xwlMUYzLFIEzGr6oSC7Ol0fIAB1DknRjMnC_SakU-By&dispatch=5885d80a13c0db1f8e263663d3faee8d69a70501aadbc2ff6a1e7e8cc0df6b0b OPEN THIS and look at the arrow it will then say the name of the project and the reference is a bunch of numbers and letters. I need to assign this somehow. my website page is here you will see the plugin.http://thegreatgathering.org/fundraisers/cultural-protection-and-exchange/ Thank you for your help. Miriam