What happens when you go through your web browser?

That usually happens because of a browser or cache issue. Try clearing your browser cache/cookies or switching to a different browser (Chrome, Firefox, Edge, etc.). If you’re doing it inside the Steam client, open the account page in an external browser instead — sometimes the built-in browser in Steam bugs out and shows a blank page.

If none of that works, change your account details directly through Steam Support > My Account > Data Related to Your Account. From there you can update most settings without relying on the buggy account edit screen.