Surname spelling

I use Family Tree Maker to store my 'family' details and am in a quandary as
to how to present surnames. My main interest is in the Playdon name and, of
course, over the years it has changed from Pladen/Pladon in Chipping Campden
and sometimes Pleaden/Pleadon and so on until the spelling that my relatives
use. My question is: Should I show their names as the incumbent wrote it at
the time of the child's christening or use the surname as it is shown in
later censuses? I do realise that many people had no idea how to spell
their names but when the names change through various generations it is hard
to keep trace of them via the computer programme. Any suggestions, please?