This is being done in an enterprise portal, v10.8. I'm not aware of any field-level editing settings. Even if I try to add an additional related table record, the date fields are grey'ed out and are un-editable.
Also (and I think this is simply a limitation of Survey123), I have 2 image fields set to an appearance of signature that that are used to capture a signature when the form is first submitted, then when it's reopened and edited, a signature to indicate the work is complete. After submitting, I'm unable to add a second signature. Any workaround for this?