Amion assigns each person a unique abbreviation. As staff come and go through the years, it can sometimes be helpful to reinitialize all the abbreviations.
To reset all the abbreviations in residency schedules, put a block schedule on screen and click on a person's name in the left-most column. Hold the Ctrl and Alt keys down and click in the abbreviation edit field in the upper-right of the infobox. The scheduler asks whether you want to reset abbreviations for all staff. Say "Yes" and all the abbreviations should then match up with names.
To reset abbreviations in attending schedules, click the face icon on the main toolbar to go to the work-preferences page. Hold the Ctrl and Alt keys down and click on the abbreviation edit field in the upper-right of the Infobox.
Once you reset the abbreviations, you can customize those that might be more clear with an extra or different letter than what the scheduler chooses for you.