A job title is a term that describes in a few words or less the position held by an employee. Depending on the job, a job title can describe the level of the position or the responsibilities of the person holding the position.

If your employee recently has been promoted, you can update their new job title at

Path : Employee > Directory > Edit

Select the new job title from the drop down list and click on the Save button.

If their new job title is not listed in the drop down list, you can always add a new job title at settings.

Path : Settings > Organization > Job Titles

Refer to this link Setting Up Job Titles.