Why is a the wrong default value being displayed in a picklist field on donations?

What Steve said, when there are picklists on an object and you have more than one record type you set the default value for the picklist on the record type not on the object. You can set a default value at the object (opportunity) level not the record level but it doesn't actually DO anything. Open your opportunity object in setup, select record type, select the record type and then edit the picklist default value. Do this for every record type for that object.