There are a couple of files in the EQ directory, for the UI.
One was the UI files and another was the scale/resolution and positioning of the files.

I'm not really sure how one would edit them, after they had been changed.

Also, in my case I wanted them to be identical across the board.
So, once I had one window working, I copied/pasted and renamed to the new toon..

Not sure why you would want them to be different from one and other.
Or how to fix them, once the settings and been homogenized across the accounts.
Maybe set the file to read only, once you've got it the way you want it?