In registering for twt cymru, what’ the difference between Display name and Username please?
It’s kind of the same as in an email account – your email account may be something like firstname.lastname@example.org but you also give your name as it should be displayed.
For example, my username is @email@example.com, and my display name is (unsurprisingly) just “Hendrik”
Also, you can change your Display Name whenever you like. I was Margaret, but I’m currently Explore Wales in Welsh (my YouTube channel). You may be able to change your Username, but that would be harder because that’s what you use to log in with and what people use to find you.