If you want to allow your users to update their records at any time, you can do it by enabling End User Edits. This way they will receive unique link, which they can use to update their entries at any time
Very often you may want to allow your users to come back and update their submitted records. For example, when your user submitted a CV, but then his address was updated. He needs some way to come back and update submission. This is when Allow End User Edits will be handy.
1) Go to Emails menu in Notifications section.
2) Check Allow end user edits item. Please notice, that to activate this feature you need to have an email field on your web form.
Remember, that your form should ask for your users' email. Only if this is true you can get all benefits from this feature. As you have most probably understood this is for emailing the link to user's submission.
A user will receive an email and will need to save it for the future use.
And finally a user will be able to update his details.