How to find the ID of a webform?
Try the Get Form ID module:


  By hovering over any form you will see a contextual link
  available. By expanding the link you will see the form ID. Click
  on the link and you will see a modal window with copyable form id and
  hook_form_FORM_ID_alter() hook suggestion.


Step 1: hover over the form.



Step 2: expanding the contextual link.


Step 3: Click on the link and a new window will open with copyable form id and hook_form_FORM_ID_alter() hook suggestion