Edit Referral / Referred By dropdown options

To add or edit / referral questions to forms globally

1. Go to Members tab
2. Click Setup on the top right hand tabs.
3. Add/remove any tick boxes or questions.
4. This will affect contact forms globally. 

This information will show under the members profile at the bottom, and can be tracked via Members > More Reports > Referrals

In this same area there is also a graph you can download as .csv  Members > More Reports > Graph - Referrals over time.