How do I edit my ffrinDiath profile.

Helo Dafydd,
Your ffrinDiaith profile is mainly your SSi profile, in addition in that profile there is a specific ffrinDiaith section you can edit, and furthermore, there is a ffrinDiaiith item under your name, top right on the SSiW page.
I hope that helps

I cannot edit in my ffrinDiaith section. I will try and edit in my SSi profile as you suggested

I was able to change it in my Account settings. Thanks for your help Louis,