Upon opening Mathematica, the notebook contents appear very large (screenshot here ). Clicking the magnification button in the bottom right corner splits the window instead of just changing the size of the font, which I would like. Screenshot of the problem: The same problem occurs when clicking Window->Magnification->100% or any other percentage. The same when clicking Format->Option Inspector->Notebook Options->Display Options->Magnification, but then luckily closing and reopening the notebook makes the sizing reasonable without the split window.
How to just change the magnification of the entire notebook without the window split? Alternatively, how to remove the right side window (the too-large font one)?
Using Mathematica 11.3 on Linux Ubuntu 18.04.2 LTS, Gnome 3.28.2 (64 bit).