Completing a Form
There are a few rules for how a form is determined to be "completed" by the end user.
An end-user is determined to have completed a form once they reach an exit point in the form or a terminal step. Forms are by default editable by end-users, but in your form settings, you can turn off edits after completion.
Note that you can design your form to have no exit points or terminal steps, and then users will never be considered "completed".