There are a few factors that can cause this issue. Initially, if you are running on a screen resolution of lower than 1920 x 1080, this is often the cause. You can try hiding the windows taskbar to be able to access the full window, but we generally recommend running a screen resolution of 1920 x 1080 at least.
Another cause may be using the Windows scaling function. If this is set to 150%, these buttons will also fall off the screen. If this is the case, we recommend you lower the Scale and layout function as found in the Windows Display Settings to 125% or lower.