I cannot tell in accurate detail where and how all of the various spellings of the name came to be. However, I do have actual family records, from photos, family bibles, old letters, census records, and other sources which lists every generation of my own direct ancestors and their parents and siblings from the present to the 1600's. I am the 11th generation of Yocom's in America, I have children, Grandchildren and Great-Grandchildren also) and I have the generational dates and names of when and who changed the spelling of our name (in my direct ancestor line). I do know that there were many branches of the family which used other spellings. However, listing my direct ancestors from my own father, generation by generation, here is the spellings of my direct ancestors. I hope this may help some who are researching this.
Starting with my father, his father, etc.:
Floyd Elmer Yocom, b Feb 13, 1904
William Henry Yocom, b May 27, 1867
William Moffatt Yocum, b Nov 9, 1841
Thornton Samuel Yocum, b 1812
Jacob Yocum (Yoakum), b 1767 (He used both
spellings)
Jacob Yoakum, b 1732
Matthias Yoakum, b 1705
Francis Jochem (Yoakum), b 1678 (He used both
spellings)
Mathias Jochem (Yoakum), b 1653 (He used both
spellings)
Heinrich Jochem (Yoakum), b early 1600's
(The Jochems were recorded in our family
history as using both names as shown since
various records show each spelling at
different occasions for the same person.)
All of these spellings are taken from what our family believes to be actual family records and more than one source.