When you're adding a participant in Teamraiser, and you search for the constituent first and find it, it populates all the fields in front of you on the participant registration screen. If any of the information that auto populates in those fields is outdated, you can't edit it there, otherwise a new constituent record will be created. You have to register the participant with the old info, then go to constituent records, find the record and update it there.  You should be able to update the constituent info right on that screen, without leaving it.