See comments in red.
To hazard a guess, you have some settings to make the text appear bigger, either through excess zoom or making the screen solution size less than 1080P (HD size) width. Both of those will switch your screen to "mobile device" size. You might also not be running your browser in a maximized window.
This is the way the software works, sorry.
If you want it horizonal, then make sure you are using a PC (or other full-sized screen). It only goes vertical on mobile devices or when you have a smaller than standard resolution.
I tried to show a logical reason or path for everything I deviated from canon on.. Less anything I guessed from books 5,6 and 7. I also tried to pair a cost to an ability.