Pre-populate several fields in Access Form

Newbie Access user. I am looking for the simplest way to pre-populate several fields when a yes/no field is checked. If the user says "yes" to a package donation, I would like several donation fields to get populated with numerical values. However I would like this data to still be editable. All the data resides within one table. Can I do something in the property sheet or is a macro required? Thanks for any help