La fonction de suggestion automatique permet d'affiner rapidement votre recherche en suggérant des correspondances possibles au fur et à mesure de la frappe.
If the UTM is being captured on the form, then the form submission history will always retain the UTM parameters from that submission. However, the contact property will continue to be overwritten with each submission. You could look to use campaigns or custom objects to capture utms at certain points for reporting with Salesforce, but without deep diving into your exact setup it's difficult to say what the best solution will end up being.