as a general rule of thumb, if you want the window to be full-screen, the hotkey is F11. Otherwise, you can try manually resizing the window so that you can view it all.
To manually resize (if able):
- scroll to the edge of the window until the cursor turns into double-arrows
- click and drag where you want the edge to be
- release mouse click
- click and drag the title-bar to position the window fully on the screen
An example for step #2 is dragging the left side of the window towards the right side of the screen.
Alternatively you could just try using a different resolution than you prefer. Find whatever works by fiddling on the screen in picture #3.