Try putting it to normal view, then full screen, then back to normal size, then enable extended view.
It's still the same. .
I can tell from your UI that you are running the Korean windows (the top bar has Korean months and days). Probably the English font from the Korean version is too big/different from standard as your UI looks all out of place.
Please set all fonts to the default (100%) size and if the problem still there I would recommend changing your settings to English and reboot windows. Maybe you will have to install the language as well.
Just go on the taskbar and search for language and change accordingly.
You will be 100% fine then.