How do I change event titles?

When my clients schedule meetings, they show up as [Their name] and [My name] in the title in Outlook. But often they are scheduling meetings for someone else (an EA scheduling for the CEO, for example). I want to change it so that they can set whatever title they want instead of this default. Is there a way to do that?

Second, how can I change the titles for meetings arleady scheduled. When I’ve adjusted the title in Outlook previously, it automatically defaulted back to the original [Their name] and [My name] format.