It is not uncommon for someone to be better known by their second (or later) given name rather than their first. The First name unused checkbox on the Naming tab of the Current Person Other Detail dialog handles this.
When checked, the full name is used in formal contexts in narrative reports, but the second given name is used in most other places. Charts also reflect this preference.
Some people’s given names were recorded in different orders in different records — for example, someone recorded as Matilda Charlotte in one place and Charlotte Matilda in another. The Name order varies checkbox, immediately below First name unused on the Naming tab, flags this.
When checked, narrative reports note that the given names were sometimes recorded in a different order, alerting the reader that the name may be encountered in more than one form. It has no effect on charts or on which name is treated as the person’s usual given name.