How change my full name in profile?

Hi, i don’t change my full name in profile, when writing says it is “invalid” and does not admit changes, including my photo.
what is the problem?
what should i do?
I want to put the full name is different from the username.

I don’t know if you can change your full name. I suppose you can change your username on LingQ.
You don’t have to show your full name to other members on the profile page.

I think you can change your “full name” unless you try to change your username at the same time.
I imagine that your e-mail address and username are connected in the database.

For now our system only allows maximum 3 words for full name. If your name has more then 3 words then that is the reason why you get “Invalid” message. We’ll do our best to allow more then 3 words for full name soon.

If your full name is composed of more than three words, and if that’s the reason you cannot change your full name, does combining, for example, two or three words by using a hyphen or two work? Is “John-Doe” treated as one word in the database?

“John-Doe” would be treated as one word, so that kind of combining will work fine.