To resize panes in the desktop app, click and hold on the title bar. When you drag it, you can place it anywhere you want or let the window snap automatically to one of the hot corners. The size and positions are going to be remembered by the App.
You can reset the workspace layout by clicking on the Default Layout button in the translation editor menu / view section
To zoom in/out the fonts in the translation editor use the increase/decreas font size buttons.
You can adjust the default font type and size for both source, target segments or TM proposals in the View menu on top View>Fonts