Having the GUI the on the same location for all characters is a quality of life improvement if you have the same layout on all characters, otherwise it's a massive pain (since you'll have to move it every time you switch characters).

Today it's unique per character, and needs to be set up on first login.

Add an option to share location for all characters. It would be nice to not override the old settings though, so just add a global entry, and switch back to char-specific when option is toggled.