The customer can update his data on the profile. The Jira administrator define which fields can be editable by all (option in the field configuration) and these ones will be available to edit in the procedure described below.
Log to the Portal.
Click on the profile photo in the right top corner.
Select Account > Profile.
Scroll to the Additional information tab and click on the value which you want to edit.
Make an edition.
Click a tick icon to confirm changes.
Information about the current customer has been updated.