Tracking web form lead sources

How to I get Infusionsoft to track our lead sources from our get a quote form on our website. This information is in the field titled “how did you hear about us” and it is currently set up as text format. IS is currently assigning my website as the lead source even though the user filling out the form selects “Google” as how they heard of us. I did read about the tracking code and it has been installed on my website. What I am reading is that this code allows tracking of these leads. But, I just did another test to see what it would do and it is still showing my website as the lead source. I hope that the only way to capture this is not for us to do it manually.