You must be an Admin to customize lead source options.

1. At the upper right, hover over your name and select Preferences.
2. At the left, click Agency.
3. Select Lead Sources.
4. Edit or Delete any of the existing lead sources, if you'd like.
5. To add a new lead source, select Click here to add a new lead source, enter the new Lead Source, then click OK.
6. To make any lead source option the default, click it's Default link.
7. When finished, click Save at bottom of page and the options will be applied to all locations.