Go to Settings > Lead Distribution > Lead Conversion Field Mapping to determine how your Lead custom fields are mapped to custom fields on the Deal, Account, and Contact records in Channeltivity. This allows your data to carry over to the Deal when the Lead is converted 

To add a field mapping, click the "Add Mapping" button and select a field from the Lead dropdown menu. You'll then click the Deal dropdown menu to select the corresponding field on the Deal. 

 If the field does not yet exist on the Deal, you can create it by clicking the "Create New Field" button.

Confirm or edit the field's name > Save. 

Click the "Add" button to add the mapping, and then click "Save" to save your changes. 

By default, the field will only be visible to Internal Users, but you can make the field read-only or editable to Partners and Distributors by going to Settings > Deal Registration > Deal Custom Fields. You'll then hover over the field and click the "Edit" link on the right to make your changes.  Learn more about this topic here: Deal Custom Fields.